Objective: To examine the association between soft drink consumption and mental health problems, including self-reported doctor-diagnosed anxiety, stressrelated problem and depression, suicidal ideation and psychological distress, among adults in South Australia. Design: Data were collected using a risk factor surveillance system. Each month a representative random sample of South Australians was selected from the Electronic White Pages with interviews conducted using computer-assisted telephone interviewing. Setting: South Australia. Subjects: Participants were aged 16 years and above. Results: Among 4741 participants, 12?5 % reported daily soft drink consumption of more than half a litre. High levels of soft drink consumption were positively associated with depression, stress-related problem, suicidal ideation, psychological distress and a current mental health condition, but not anxiety. Overall, 24?0 % of those having suicidal ideation reported consuming more than half a litre of soft drink per day. In the multivariate analysis, after adjusting for sociodemographic and lifestyle factors, those who consumed more than half a litre of soft drink per day had approximately 60 % greater risk of having depression, stress-related problem, suicidal ideation, psychological distress or a current mental health condition, compared with those not consuming soft drinks. The soft drink to total fluid consumption ratio had similar associations with mental health problems. Conclusions: There is a positive association between consumption of soft drinks and mental health problems among adults in South Australia.