Recreational drug (marijuana, lysergic acid diethylamide or LSD, speed, cocaine, and "other") exposures of women with primary infertility were compared with those of a matched control group of women with proven fertility. Women who reported smoking marijuana had a slightly elevated risk for infertility due to an ovulatory abnormality (RR = 1.7, 95% CI = 1.0 to 3.0). The risk was greatest among women who had used marijuana within one year of trying to become pregnant (RR = 2.1, 95% CI = 1.1 to 4.0). No consistent frequency or duration of use effects could be demonstrated, and the risk was confined to low-frequency users. Risks associated with the use of other drugs were not elevated. The risk of infertility from a tubal abnormality associated with cocaine use was greatly increased (RR = 11.1, 95% CI = 1.7 to 70.8). Our results are consistent with animal studies suggesting that smoking marijuana may cause a transient disruption of ovulatory function. The possibility that cocaine exposure influences the development of tubal infertility needs further investigation.