<p>Self-injurious behavior (SIB) is highly prevalent in autistic individuals with an intellectual disability (ID). However, only a few studies have focused on autistic adult populations, and no data on prevalence, treatment, and impact on the day-to-day lives of adult residents is available for Germany, in particular. We conducted a postal survey of residential care facilities. We assessed different topographies, severities, and frequencies of SIB, as well as treatment strategies and the impact of SIB on day-to-day life. The overall prevalence of SIB reported by 60 residential care facilities was 51.3%. Autistic residents with ID who exhibit SIB displayed more than 4 topographies of SIB, on average, nearly half (47%) displayed multiple topographies daily, and approximately 17% engaged in severe SIB daily. Of those residents, 67.7% were reported to receive some systematic intervention within the facility, and 95.6% experienced at least one type of impact on their day-to-day life due to SIB. This study provides the first prevalence data for SIB in autistic adults with an ID in Germany and the first data on treatment within facilities, as well as the potential impacts on day-to-day life. The prevalence results fell in line with previous research, and we provide a more detailed picture of the forms, frequencies, and severities of self-injurious behavior in the German adult autistic population.</p>