Some older patients on treatment wards suffer from poor mental status in addition to a primary illness condition. This research 1) compared the relative prevalence of cognitive dysfunction when indexed by a mental status questionnaire (MSQ), physician reports, and nurse ratings, respectively, and 2) examined relationships of the MSQ to other variables. The sample was the entire inpatient population on medical and surgical wards at two general hospitals during a one-week period. Data were obtained from the patients (i.e., the MSQ), case notes by physicians (i.e., diagnoses or symptoms indicative of cognitive dysfunction), and ward nuses (i.e., ratings on several variables). The findings were that prevalence of cognitive dysfunction was greater by the MSQ than by physician reports, than by nurse ratings. Against the criterion of MSQ classification, both physicial reports and nurse ratings exhibited false positive and false negative errors; however, false negative errors were more frequent. The strong correlates of MSQ included capacity for independent living, use of geriatric chair, and physician evaluation. Other signs of normalcy or dysfunction were specific to only one MSQ category: tube feeding, restraint, and basic function capability.