We previously documented that periodic limb movement disorder (PLMD) patients report more psychopathological symptoms on the MMPI than obstructive sleep apnea (OSA) patients, who in turn report more symptoms than primary snorers (PS). The purpose of this study was to replicate and extend these findings on an independent patient sample using an alternative measure, the Symptom Checklist 90 - Revised (SCL-90-R). Of 109 consecutive diagnostic polysomnography (PSG) referrals to a Sleep Disorders Clinic, we studied every patient with PLMD (n=11, 6 males and 5 females; mean age = 55 years). Two comparison groups were developed by randomly selecting one OSA and one PS patient from those matching PLMD subjects on gender and age. Subjects completed the SCL-90-R before undergoing sleep interview, physical examination, 12-channel diagnostic PSG, and daytime MSLT. Analysis of covariance indicated that, even after controlling for MSLT latency, the SCL-90-R General Severity Index was significantly higher (and more likely to be elevated) in the PLMD subjects than in OSA or PS subjects. PLMDs also scored significantly higher than both of the other groups on the Obsessive- Compulsive, Interpersonal Sensitivity, and Depression scales. Corresponding differences emerged in the prevalence of elevated SCL-90-R scores; elevation was 1.7 to 3.6 times more likely in PLMD than in OSA and PS. We conclude that irrespective of daytime sleepiness, patients with PLMD are more likely than those with PS or OSA to experience obsessionality, compulsivity, concentration difficulties, dysphoria, fatigue, low motivation, and interpersonal oversensitivity. Thus, the relative ranking of psychopathology symptoms previously observed in patients with PLMD, OSA, and primary snoring was replicated across different samples and measures.