Studies of clinical cognitive screening tests began in the 1960s, and ten instruments have been reported in the English literature. In this study, we have compared the widely used Mini-Mental State Examination developed by Folstein with a reportedly enhanced version, the Modified Mini-Mental State Examination devised by Teng, using a sample of 250 patients (inpatients, outpatients, emergency). We have come to the conclusion that the modifications brought about by Teng result in a minor improvement of the validity of the Mini-Mental State Examination in a psychiatric patients in a general hospital.