In previous studies of the relationship between stress and menstrual cycles, stress has been found to be associated with longer cycles, to be associated with shorter cycles, and to have no association with cycle length. Some of the menstrual cycle changes that have been attributed to stress are similar to those experienced by women during perimenopause. In an effort to see whether an association between psychological stress and menstrual cycle characteristics can be detected in women approaching menopause, this study examines this relationship in perimenopausal women who are participants in the Tremin Research Program on Women's Health. The analyses used prospectively recorded bleeding data and retrospectively captured life-event data. A single-year cross-sectional analysis of data from 206 women shows no correlation between stress level, as measured by total number and severity of stressful life events, and cycle characteristics, including interval length, duration of bleed, and variability in both of these factors, nor are there significant differences in cycle characteristics between subgroups of women with different overall levels of stress. In analyzing stress levels and cycle characteristics across 2 years, however, women with marked increases in their level of stress (n = 30) are shown to have decreased length (-0.2 days/cycle) of menstrual cycle intervals and decreased duration of bleed (-0.1 day/cycle) compared with increases in these measures (+2.9 days/cycle for cycle interval; +0.3 days/cycle for duration of bleed) among women with no marked change in stress level (n = 103); t-tests indicate that these differences are significant (p < .05).