The efficacy of anabolic steroid therapy has often been challenged because of equivocal clinical evidence of weight gain. In view of this challenge, 21 chronically underweight, geriatric patients in a state hospital were chosen for a study to determine the effect of a new synthetic anabolic prep mation, norbolethone. Long-term weight charts were used to determine confidence limits. After a one-month placebo trial, placebo responders were identified; then the active preparation was given for fourteen weeks. The data indicated that 8pUriOU8 results can be obtained if strict criteria are not used for changes in body weight. Of the 21 etudy patients, as many as 18 could have been reported as showing a weight gain if only a short pre-study period had been used for the baseline. However, when the placebo responders and yearly weight fluctuations were accounted for, only 4 patients showed significant gains in weight, and only 2 of these maintained their gaine until the completfon' of the anabolic phase of the etudy.Unless stringent criteria are applied, gross body weight alone cannot be used as a reliable index of the therapeutic &ect of anabolic ste~oids.Problems in design and data handling have often made the study of the clinical effects of anabolic steroids difficult to evaluate. There is considerable information regarding the value of an anabolic stimulus in the management of chronic illness, and the nitrogen-retaining effect is well documented. However, the data on body weight gains are often equivocal (1-3).The fact that body weight may remain stable in the presence of an anabolic effect, or may increase in the presence of a non-anabolic effect or concomitant illness indicates the need for quantitative measurement of the actions of anabolic agents; this has been pointed out by others (1, 4). The clinician often cannot conduct nitrogen balance studies, so he has to rely on changes in body weight as the primary criterion in determining the efficacy of treatment. The literature is vague on this important criterion; weight gains are expressed as