Seventy-six obese women with a mean age of 42.1 years and weight of 106.0 kg were randomly assigned to one of three treatments:(a) very low calorie diet alone;(b) behavior therapy alone; or their combination (ie combined treatment). Weight losses for the three conditions at the end of treatment were 13.1, 13.0, and 16.8 kg, respectively, with losses for combined treatment significantly greater than those for the two other conditions. Weight losses 1 year after treatment were 4.7, 6.6, and 10.6 kg, respectively. A significantly greater percentage of subjects in the behavior therapy alone (36 percent) and combined treatment conditions (32 percent) maintained their full end-of-treatment weight losses than in the very low calorie diet alone condition (5 percent). Five years after treatment, a majority of subjects in all three conditions had returned to their pretreatment weight, and 55 percent of the total sample had received additional weight reduction therapy. The short and long term effects of treatment are discussed in terms of their implications for practice and research.