To date, no studies have evaluated for differences in subjective and objective measures of sleep disturbance in oncology outpatients with and without pain. This descriptive cross-sectional study, recruited 182 patients with mixed types of cancer from two radiation therapy (RT) departments at the time of the patient's simulation visit. Approximately 38% of the sample reported moderate to severe pain, with a mean worst pain intensity of 6.2 (SD = 2.4) on an 11-point scale. Significant main effects of pain group were found for the PSQI subscales of quality and disturbance, as well as the global PSQI score with patients in pain reporting higher scores than patients without pain. Significant main effects of pain group were found for the GSDS subscales of quality, medications, and daytime sleepiness, as well as the total GSDS score with patients in pain reporting higher scores than patients without pain. In addition, significant differences in objective reports of nocturnal sleep/rest, daytime wake/activity, and circadian activity rhythm parameters between pain groups were found. These data indicate that pain is prevalent among oncology outpatients and substantially impairs sleep. Further research is warranted to describe more completely the effects of age and gender in the context of pain and sleep disturbances in oncology outpatients prior to radiation therapy.