The prevalence of snoring and obstructive sleep apnea syndrome increases with age. Upper airway obstruction during sleep occurs when the dilator muscles are unable to overcome the negative pharyngeal pressure. The very important muscle dilator of the upper airway is the genioglossus muscle (GG). Our previous study showed an increase in GG-EMG activity during progressive hypoxia. In the present study a hypoxic increase in GG-EMG activity in response to hypoxia was investigated in two groups of 10 healthy subjects each: aged 29.1 +/- and aged 53.2 +/-2.3. The older humans showed reduced response of GG to hypoxia. We suggest that the biological aging process may be a risk factor for the obstructive sleep apnea syndrome.