Purpose:The objective of the study was to assess whether the history of psychiatric treatment was associated with (1) body weight and BMI on admission for bariatric surgery, (2) weight loss > 5 kg prior to bariatric surgery, and (3) postoperative body weight reduction. Methods: Data from medical records of all consecutive patients admitted for surgical treatment of obesity in the 2nd Department of General Surgery Jagiellonian University Medical College were obtained. There were 1452 records of patients who underwent bariatric surgery between 2009 and 2021 included in the study. Results: History of psychiatric treatment was found in 177 (12%) of the sample and was inversely associated with body weight and BMI on admission for surgery in women. Men with history of psychiatric treatment were 54% less likely to lose > 5 kg before the surgery (OR = 0.46 95% CI = 0.24–0.88). Both in men and women %TWL did not differ significantly by history of psychiatric treatment (Me: 40.7 vs. 45.9; p = 0.130 and Me: 27.0 vs. 23.9; p = 0.383, respectively). After adjustment for covariates no association was found between history of psychiatric treatment and body weight reduction one year after surgery. Conclusion: Although men with preoperative history of psychiatric treatment had lower odds of losing weight before the surgery, psychiatric treatment did not differentiate the effectiveness of bariatric treatment in 1 year of observation. Bariatric surgery appears to be an effective obesity care for people treated for mental disorders.