BACKGROUND: Few empirical reports of studies examining the association between bariatric after care support group attendance and weight loss outcomes have been published. The present study investigated the association between the number of support group meetings attended and percentage of excess weight loss at 12 months after gastric banding surgery. The setting was a private practice at which no-cost, professionally led support group meetings were held weekly. METHODS: The medical records and support group attendance logs were examined for the dates of attendance, frequency of attendance (or no attendance) in relation to the percentage of excess weight loss (n = 102; 88.2% women; mean age 45.6 ± 11.3 years; mean baseline body mass index 46.4 ± 8.8 kg/m(2)). Linear regression models were used to assess the relationship between the number of group meetings attended and the percentage of excess weight of loss with age and baseline body mass index used as optional independent variables. RESULTS: A significant linear relationship was found between support group meeting attendance and the percentage of excess weight loss with simple regression analysis (adjusted R(2) = .061, P = .007), with age (adjusted R(2) = .100, P = .002) and the baseline body mass index added to the model (adjusted R(2) = .072, P = .011). CONCLUSION: The results of the present study add to the growing evidence of the positive relationship between the frequency of support group attendance and the percentage of excess weight loss. Future studies should examine patient motivational characteristics in relation to support group participation and other aspects of compliance with aftercare recommendations to investigate unique effects of each part of the treatment program on weight loss outcomes.