The experience with 83 patients aged 60 or older from the Stanford Sleep-Wake Disorders Clinic is compared with that in 423 younger clinic patients seen during the same two-year period. Each patient received a medical, psychologic and polysomnographic evaluation. The final diagnoses were recorded according to the Diagnostic Classification System of the Association of Sleep Disorders Centers. The most common major diagnoses in the elderly group were sleep apnea syndrome (39 percent) and periodic movements-restless legs syndrome (18 percent). These syndromes showed a significantly greater prevalence in the older than in the younger patients (p less than .001), and were found in 68 percent of the elderly group. The elderly manifested more objective signs of sleep disturbance, including more wake time after sleep onset, and more frequent and longer awakenings; moreover, fewer of them experienced stage-4 sleep. The diagnostic findings seemed to indicate that complaints about sleep-wake functioning in many elderly patients may be a result of specific pathologic sleep disturbances.