High DDE and DDT concentrations were found to be associated with shortened menstrual cycle length in Laotian immigrants to the United States. We examined this issue in a sample of young Chinese women. A total of 60 women aged 20-24 years were enrolled in three maternal and child health clinics (20 from urban, 20 from suburban, 20 from rural) in Shanghai, China, and vicinity, in 1998. Of these women, 47 who did not use hormonal contraceptives and had valid menstrual cycle characteristics were included in the analysis for associations among serum DDE and DDT concentration and menstrual cycle length, duration of menses, and heaviness of menstrual flow. In univariate analysis, higher p,p'-DDE concentration was associated with longer menstrual cycle length (0.66 day per 10 microg/L, 95% confidence interval [CI]: 0.21, 1.11 day). With adjustment for age, body mass index, education, occupation, and resident location, the estimate was 0.42 day (95% CI: -0.35, 1.19 day). p,p'-DDE was not associated with duration of menses or heaviness of menstrual flow. Neither p,p'-DDT nor o,p'-DDT were associated with menstrual cycle length, duration of menses or heaviness of menstrual flow. The study largely suggests no association between DDE and DDT concentrations and menstrual cycle characteristics in young Chinese women, though the weak-to-no correlation of DDE with menstrual cycle length merits further study.