The aim of the study was to examine the oral health and treatment needs of chronically hospitalized psychiatric patients in Israel. Ten percent of the patients hospitalized for more than 2 years in the 18 psychiatric institutions in Israel were selected at random. The dental status (DMF-T index) was calculated, demographic and medical data were retrieved from the files. Of the 431 patients examined (250 men, 181 women, average age 54 years) 312 patients had only partial natural dentition. The average DMF-T score was 26.74 (out of 32), one of the highest in the literature. The caries component accounted for 2.3% of the DMF-T, the missing teeth component 72% and the restored teeth component 5%. There was an adverse correlation between age and caries and between duration of hospitalization and number of teeth. The average number of carious and missing teeth was higher than in the healthy population. No all-edentulous patients had dentures. These findings confirm the urgent need for an intervention program to improve dental health care in high-risk, difficult-to-treat, psychiatric chronic inpatients.