The authors present a new approach for evaluation and counseling of teratogenic risk, The Motherisk program in Toronto presently deals with 60 inquiries per day from the public and health professionals. Most calls are answered through the telephone, and 16–20 women per week are scheduled for our clinic following exposure to known or suspected teratogens, to new drugs with sparse information, to chronic drug therapy, or drugs of abuse. Also seen in clinic are women who want to he counseled or whose physicians want them to meet us due to high levels of anxiety. Since its inception in 1935 the Program has been very effective in preventing unnecessary terminations of otherwise wanted pregnancies. In addition to the clinical service we followup the outcome of these prospectively collected exposures, thus creating a large data base necessary to verify safety/risk of various agents. During the last 2 years Motherisk has completed singly, or in collaboration, large prospective studies on gestational exposure to lithium, antiepileptics, cocaine, and fluexitime. To study the reproductive risks of cocaine we compared first-trimester exposure to cocaine with two control groups. Infants exposed to cocaine did not have higher rates of any adverse perinatal outcome. Their cognitive function at 16 months of age was identical to the control infants. Meta analysis of all studies assessing gestational risks of cocaine reveals that the results of these studies were dependent on the type of comparison conducted. When babies exposed to cocaine were compared with middle class nonusers, the cocaine groups seemed to he more often different from their controls. Conversely, when cocaine-exposed infants were compared with babies of women exposed to other drugs of abuse but not cocaine, most of these differences cancelled out, suggesting that clustering of other risk factors may cause some of these adverse effects.