This study demonstrated that cigarette smoking was associated with an increase in both time to conception (among 2817 fertile women) and risk of primary infertility (among 1818 infertile women and their primiparous control subjects). The average time to conception was 4.3 months for women who never smoked, 4.6 months for those who smoked in the past, and 5.1 months for those who currently smoked. The delay in conception for current smokers remained significant after adjusting for confounders (risk ratio of 0.9 (0.8 to 1.0)). Additionally, current smokers were at increased risk of primary infertility (odd ratios of 1.9 (1.5 to 2.3)). For alcohol use, the average time to conception and risk of primary infertility did not vary by level of consumption. The average time to conception was significantly shorter for women who had used marijuana regularly and for women who had ever used cocaine than for women who had never used these drugs. Because of the increased use of marijuana and cocaine among young adults, further investigations of these associations are needed.