The present study examined the psychometric properties of the Daily Sleep Diary (DSD), an instrument developed for monitoring sleep among chronic pain patients. As part of a comprehensive evaluation, 46 chronic pain patients completed the DSD each morning. Items assessed the number of hours slept, length of sleep onset, frequency of awakenings during the night that resulted in trouble falling back to sleep, early morning awakening, quality of sleep, lack of restfulness, and the previous night's sleep compared to usual sleep. Reliability coefficients were significant. The sleep diary items significantly correlated with other retrospective measures of sleep. Duration of pain complaint was related to delayed sleep onset and lower quality of sleep. Pain severity was related to fewer hours slept and delayed sleep onset. The DSD items correlated with measures of both depression and anxiety. The results emphasize the importance of including sleep in both assessment and treatment of chronic pain patients.