The objective of this study was to estimate the rate of hidden psychiatric morbidity (HPM) in a study population and to compare the assessment of the primary health care (PHC) physician with that of the psychiatrist. All patients seen for 2 wks were rated by a PHC physician according to a 5-point severity rating scale and diagnostic classification. One-third of the Ss were interviewed by a psychiatrist using the clinical interview schedule. The HPM is high (31%), representing 67% of the total psychiatric morbidity (46%). This is due to the low identification index of the physician (33%). The higher the severity of the illness as rated by the PHC physician, the more likely was the case to be considered a clinically significant psychiatric case. On the other hand, the specificity (95%) and predictive value (86%) were high, i.e., the physician was likely to be correct when making a positive diagnosis. There was a significant difference in the ratings of the psychiatrist and the physician. Psychiatric illness with somatic symptoms constituted the largest proportion of diagnostic categories as judged by the psychiatrist (31.6%). Patients labeled by the PHC physician to have physical illness in a neurotic personality were usually missed psychiatric cases.