This study aims to investigate the association between earlier sexual abuse and polysubstance abuse among persons in alcohol, drug and gambling addiction treatment in Greenland. The study included 431 individuals treated in 2017-2019. Data on exposure (sexual abuse), outcome (polysubstance abuse), and potential confounders (age, sex, school education, further education, labour market affiliation, physical abuse and emotional abuse) were extracted from The National Database on Substance Abuse Treatment. Polysubstance abuse was defined as both smoking cannabis more than once a week and having an AUDIT score >15. Logistic regression was used to estimate odds ratios (ORs). In total, 61% reported having been sexually abused. Women were more often sexually abused and had more often been physically and emotionally abused when compared to men. Polysubstance abuse (OR 2.06, 95% CI: 1.22; 3.48) and cannabis abuse (OR 1.89, 95% CI: 1.20; 2.98), but not alcohol abuse, were more frequent in sexually abused when compared to non-victims of sexual abuse. This study found polysubstance abuse to be more frequent in sexually abused treatment seekers. It is recommended that the findings are taken into account in the planning of treatment services and in training of counsellors.