To elucidate the effects of aging on ventilation in nocturnal disturbed breathing (NDB), we investigated 16 subjects aged 65 years or over with system developed by the authors using a respiratory inductive plethysmography connected to a personal computer. The subjects underwent 10 hours of continuous monitoring of lung volume and SaO2. Significant desaturation (SDS, greater than 4% drop in SaO2 from baseline value) and desaturation index [DI, sigma SDS(%) X duration (hr)] were calculated using the same program. The subjects with SDS below 50 were assigned to group A (n = 9, mean age = 79.7, male:female = 8:1) and the remaining subjects with SDS over 50 (n = 7, mean age = 74.7, male:female = 3:4) to group B. There was no significant difference in ventilatory parameters between group A and B. We then compared the male group (n = 11, mean age = 77.8) with the female group (n = 5, mean age = 76.8). The number of SDS in the female group (101.4 +/- 34.7) was significantly greater than that of the male group (33.4 +/- 8.3*, p less than 0.02), while minute ventilation of the female group (5.25 +/- 0.31 l/min) was significantly smaller than that of the male group (8.86 +/- 1.36* l/min, p less than 0.05). DI was found to significantly correlate with the SaO2 nadir and the number of apnea and SDS. There was no significant relationship between SDS and ventilatory parameters in this study. NDB among elderly female may be of more importance than has been reported.