During 2011-2016, HIV outbreaks occurred among people who inject drugs (PWID) in Athens, Greece; Bucharest, Romania; Dublin, Ireland; Glasgow, Scotland; Luxembourg; southeastern Saskatchewan, Canada; Scott County, Indiana, United States; and Tel Aviv, Israel. Factors common to several many of these outbreaks included: community economic problems, homelessness, and changes in drug injection patterns. The outbreaks differed in size (from under 100 to over 1000 newly reported HIV cases among PWID) and in the extent to which combined prevention had been implemented prior, during and after the outbreaks. Countries need to ensure high coverage of HIV prevention services; coverage higher than current UNAIDS recommendation may be needed in areas in which short acting drugs are injected. In addition, monitoring of PWID with special attention for changing drug use patterns, risk behaviors and vulnerable subgroups, such as homeless PWID, needs to be in place to prevent or rapidly detect and contain new HIV outbreaks.