The present study examines the association of obesity, cigarette smoking, alcohol consumption, and exercise with the prevalence of menstrual cycle disorders among 2912 women aboard U.S. Navy ships. Self-administered surveys obtained information on weight, height, cigarette smoking, alcohol consumption, and exercise. Participants also indicated whether they experienced cramps or pain during their period requiring medication or time off work, bleeding between periods, excessive frequency of periods, heavy periods, periods lasting for longer than a week, scanty menstrual flow, and irregular periods during the past 90 days. Women ranged in age from 18 to 49 years, with an average of 26 years. After adjustment for age, race, and pay grade, current cigarette smoking was associated with increased risk of all menstrual symptoms and cycle disorders. As compared with nonsmokers, current smokers were at increased risk of cramps or pain requiring medication or time off work (odds ratio [OR] = 1.13, 95% confidence interval [CI] = 1.03, 1.25), bleeding between periods (OR = 1.22, CI = 1.09, 1.38), excessive frequency of periods (OR = 1.33, CI = 1.17, 1.51), heavy periods (OR = 1.17, CI = 1.06, 1.29), periods lasting longer than a week (OR = 1.31, CI = 1.16, 1.48), scanty flow (OR = 1.13, CI = 1.01, 1.29), and irregular periods (OR = 1.14, CI = 1.05, 1.24). Obesity, exercise, and alcohol consumption did not show consistent associations with menstrual symptoms or cycle disorders. Logistic regression models that included age, race, pay grade, and all behavioral and lifestyle variables indicated only cigarette smoking was associated with an increased risk of bleeding between periods (OR = 1.33, CI = 1.05, 1.68), excessive frequency of periods (OR = 1.38, CI = 1.21, 1.58), periods lasting longer than a week (OR = 1.45, CI = 1.13, 1.84), and irregular periods (OR = 1.25, CI = 1.05, 1.47). Although the lifestyle factors are all potentially modifiable, results suggest that only interventions targeted at smoking cessation might be useful in reducing the prevalence of menstrual symptoms, cycle disorders, and time lost from work.