Background For people with physical, sensory and cognitive limitations due to stroke, the routine practice of oral health care (OHC) may become a challenge. Evidence‐based supported oral care intervention is essential for this patient group. Objectives To compare the effectiveness of OHC interventions with usual care or other treatment options for ensuring oral health in people after a stroke. Search methods We searched the Cochrane Stroke Group and Cochrane Oral Health Group trials registers, CENTRAL, MEDLINE, Embase, and six other databases in February 2019. We scanned reference lists from relevant papers and contacted authors and researchers in the field. We handsearched the reference lists of relevant articles and contacted other researchers. There were no language restrictions. Selection criteria We included randomised controlled trials (RCTs) that evaluated one or more interventions designed to improve the cleanliness and health of the mouth, tongue and teeth in people with a stroke who received assisted OHC led by healthcare staff. We included trials with a mixed population provided we could extract the stroke‐specific data. The primary outcomes were dental plaque or denture plaque. Secondary outcomes included presence of oral disease, presence of related infection and oral opportunistic pathogens related to OHC and pneumonia, stroke survivor and providers' knowledge and attitudes to OHC, and patient satisfaction and quality of life. Data collection and analysis Two review authors independently screened abstracts and full‐text articles according to prespecified selection criteria, extracted data and assessed the methodological quality using the Cochrane 'Risk of bias' tool. We sought clarification from investigators when required. Where suitable statistical data were available, we combined the selected outcome data in pooled meta‐analyses. We used GRADE to assess the quality of evidence for each outcome. Main results Fifteen RCTs (22 randomised comparisons) involving 3631 participants with data for 1546 people with stroke met the selection criteria. OHC interventions compared with usual care Seven trials (2865 participants, with data for 903 participants with stroke, 1028 healthcare providers, 94 informal carers) investigated OHC interventions compared with usual care. Multi‐component OHC interventions showed no evidence of a difference in the mean score (DMS) of dental plaque one month after the intervention was delivered (DMS –0.66, 95% CI –1.40 to 0.09; 2 trials, 83 participants; I2 = 83%; P = 0.08; very low‐quality evidence). Stroke survivors had less plaque on their dentures when staff had access to the multi‐component OHC intervention (DMS –1.31, 95% CI –1.96 to –0.66; 1 trial, 38 participants; P < 0.0001; low‐quality evidence). There was no evidence of a difference in gingivitis (DMS –0.60, 95% CI –1.66 to 0.45; 2 trials, 83 participants; I2 = 93%; P = 0.26: very low‐quality evidence) or denture‐induced stomatitis (DMS –0.33, 95% CI –0.92 to 0.26; 1 trial, 38 participants; P = 0.69; low‐quality evidence) among participants receiving the multi‐component OHC protocol compared with usual care one month after the intervention. There was no difference in the incidence of pneumonia in participants receiving a multi‐component OHC intervention (99 participants; 5 incidents of pneumonia) compared with those receiving usual care (105 participants; 1 incident of pneumonia) (OR 4.17, CI 95% 0.82 to 21.11; 1 trial, 204 participants; P = 0.08; low‐quality evidence). OHC training for stroke survivors and healthcare providers significantly improved their OHC knowledge at one month after training (SMD 0.70, 95% CI 0.06 to 1.35; 3 trials, 728 participants; I2 = 94%; P = 0.03; very low‐quality evidence). Pooled data one month after training also showed evidence of a difference between stroke survivor and providers' oral health attitudes (SMD 0.28, 95% CI 0.01 to 0.54; 3 trials, 728 participants; I2 = 65%; P = 0.06; very low‐quality evidence). OHC interventions compared with placebo Three trials (394 participants, with data for 271 participants with stroke) compared an OHC intervention with placebo. There were no data for primary outcomes. There was no evidence of a difference in the incidence of pneumonia in participants receiving an OHC intervention compared with placebo (OR 0.39, CI 95% 0.14 to 1.09; 2 trials, 242 participants; I2 = 42%; P = 0.07; low‐quality evidence). However, decontamination gel reduced the incidence of pneumonia among the intervention group compared with placebo gel group (OR 0.20, 95% CI 0.05 to 0.84; 1 trial, 203 participants; P = 0.028). There was no difference in the incidence of pneumonia in participants treated with povidone‐iodine compared with a placebo (OR 0.81, 95% CI 0.18 to 3.51; 1 trial, 39 participants; P = 0.77). One OHC intervention compared with another OHC intervention Twelve trials (372 participants with stroke) compared one OHC intervention with another OHC intervention. There was no difference in dental plaque scores between those participants that received an enhanced multi‐component OHC intervention compared with conventional OHC interventions at three months (MD –0.04, 95% CI –0.33 to 0.25; 1 trial, 61 participants; P = 0.78; low‐quality evidence). There were no data for denture plaque. Authors' conclusions We found low‐ to very low‐quality evidence suggesting that OHC interventions can improve the cleanliness of patient's dentures and stroke survivor and providers' knowledge and attitudes. There is limited low‐quality evidence that selective decontamination gel may be more beneficial than placebo at reducing the incidence of pneumonia. Improvements in the cleanliness of a patient's own teeth was limited. We judged the quality of the evidence included within meta‐analyses to be low or very low quality, and this limits our confidence in the results. We still lack high‐quality evidence of the optimal approach to providing OHC to people after stroke.