We have evaluated 36 consecutive systemic lupus erythematosus (SLE) female patients, age 18-39 years, without current or previous alkylating therapy, in order to determine the prevalence of the menstrual disturbances and their clinical, hormonal and therapeutic associations. Seventeen patients presented normal cycles, whereas menstrual alterations were observed in 19. Ovarian function was generally preserved in these groups. Sub-clinical thyroid disease (normal free T4 and elevated TSH) and slightly increased prolactin levels were detected in 8% of patients, with comparable frequencies in both groups. Similarly, the current use of azathioprine was not associated with menstrual disturbances. Percentages of prednisone current use (P = 0.3), mean dose (P = 0.062), and percentages of patients on high doses (> or = 30 mg/day; P = 0.09) were comparable in patients with or without menstrual alterations. In contrast, the mean SLEDAI levels (P = 0.02) and the frequency of patients with SLEDAI > or = 8 (P = 0.008) were higher in patients with irregular cycles. Interestingly, 5/7 (71%) of the patients with menstrual disturbances and a new significant flare (SLEDAI > or = 8) were evaluated before the introduction of high dose steroid, supporting the idea that disease activity is a major factor in menstrual disorders in SLE patients without alkylating therapy.