BackgroundDepression and anxiety are commonly experienced among gay, bisexual and other men-who-have-sex-with-men (gbMSM). We explored factors associated with improvements in mental health symptoms among gbMSM with abnormal depression and anxiety scores over a period of four years, in Vancouver, Canada. MethodsSexually active gbMSM ≥16 years of age were recruited using respondent-driven sampling from February 2012 to February 2015. Participants completed a computer-assisted questionnaire which included the Hospital Anxiety and Depression Scale (HADS), and psychometric scales to measure loneliness, self-esteem and social connectedness, every 6 months until July 2019. Generalized linear mixed models were used to assess factors associated with normal/borderline HADS scores (<11) following a previous abnormal score (≥11) for each of anxiety and depression subscales. ResultsWe recruited 694 participants, of whom 580 had at least one follow-up visit. Across all visits, 43.6 % of participants ever had abnormal anxiety scores and 16.2 % ever had abnormal depression scores. Among those with abnormal anxiety scores, 34.9 % of follow-up visits demonstrated reductions in anxiety scores. Among those with abnormal depression scores 51.0 % of follow-up visits demonstrated reductions in depression scores. Reductions in anxiety scores were associated with increased self-esteem, decreased loneliness and the number of gbMSM seen/spoken to in the previous month. Reductions in depression scores were associated with increased self-esteem, decreased loneliness and having a regular partner. ConclusionImprovements in mental health symptoms were frequently observed. Social connectedness was related with improved anxiety and depression symptoms. Interventions to improve social connectedness may help to improve mental health for gbMSM.