The prevalence of obstructive sleep apnea syndrome in patients up to the age of 60 is known to be two times higher in men then in women. Hormonal changes during menopause might underlie changes in this relationship in the elderly. This study was designed to detect differences in the type and frequency of sleep-disordered breathing between women and men over the age of 65 years, having the same body mass index. The study was conducted using a matched-pair approach consisting of a sample population of 40 pairs of patients over the age of 65. All patients met the following exclusion criteria: age below 65, heart failure, chronic obstructive lung disease. Polygraphy was conducted by means of a portable recorder. All measured indices were higher in men than in women. The apnea index was 2.8 +/-4.1 in men and 0.6 +/-1.4 in women. The apnea/hypopnea index was 10.2 +/-11.4 and 4.8 +/-3.9, respectively. These differences were significant (P<0.05). Significant differences also were observed when central (men 8.1 +/-13.1, women 3.1 +/-8.2), mixed (men 5.1 +/-11.4, women 0.4 +/-1.3), and obstructive (women men 8.6 +/-20.1, 1.0 +/-4.3) apnea indices were compared. In conclusion, the study demonstrates that elderly patients showed gender-dependent differences in the type and frequency of sleep-related breathing disorders. Men suffered from all kinds of apnea more frequently than women.