The purpose of this study was to examine whether age and perceived stress were independent factors affecting blood pressure variation associated with changing daily microenvironments among women employed outside the home. The subjects of this study were 91 women from the same workplace (age 33.8 +/- 8.5 years; range 18.2-49.3 years) who wore an ambulatory blood pressure monitor over the course of one workday. Blood pressure averages were calculated at work (11 am to 3 pm), home (6 pm to approximately 10 pm), and during sleep (approximately 10 pm to 6 am). The stressfulness of the work and home microenvironments was rated by self-report on a scale of 0 (low) to 10 (high). A repeated measures analysis of covariance was used to assess the cross-classified effects of perceived stress (work stressed [work > home stress; N = 41], home stressed [home > work stress; N = 39], and equally stressed [work = home stress; N = 11]) and age group (18.0-29.9 years, N = 31; 30-39.9 years, N = 34; 40-49.9 years, N = 26) on the blood pressure averages with daily environment as a within-subject factor and measures of body fat and menstrual phase as covariates. Work-stressed women had higher systolic blood pressure at work, home, and during sleep than home-stressed women (127 vs 119, P < 0.001; 124 vs 119, P < 0.05, and 111 vs 104, P < 0.005). There were similar patterns for diastolic blood pressure. Age showed a U-shaped relationship, with women in the 30-39.9 year age range generally having lower systolic and diastolic blood pressures at work (P < 0.05), home (P < 0.10), and during sleep (P < 0.05) than younger and older age groups. The interaction between age group and perceived stress level was not significant, so that the variation in blood pressure associated with perceived stress (work stressed, home stressed, and equally stressed) was similar in each age group. Although blood pressure changes with age, environment-related stress, particularly job-related stress, continues to have a significant effect on daily blood pressure variation. However, data also indicate that blood pressure measured during the day may not necessarily show a linear increase with age.