The effectiveness and tolerance of a non-amphetaminic anorexiant drug has been evaluated in a short-term and in a long-term clinical trial in simple obesity and in refractory obesity. In the short-term 'crossover' trial, a more evident effectiveness and tolerance result when the anorexiant is given in a late phase of treatment. The association of an anorexiant drug with the hypocaloric diet was seen to be effective in the treatment of so-called refractory obesity. In the evaluation of the long-term treatment it is seen that weight loss is greater and remains so farr longer periods in patients receiving anorexiant, as compared to controls. This is related to a better maintenance of a restricted calorie regimen. Mazindol did not affect the improvement of glucose tolerance and insulin secretion which follows the weight reduction.