The present study investigates the extent to which the physicians' diagnosis of depression was influenced by the reason that patients gave for seeking help, i.e. the reason for encounter. The level of correspondence between the somatic diagnoses of 20 GPs and the self-ratings of 862 patients from the regions of North Rhine and Southern Baden in regard to the presence of a depressive syndrome was recorded. In addition to the somatic diagnosis of depression (yes/no), the reason for encounter as well as primary and secondary diagnoses of the participating GPs were also documented. The results show that approximately 10% of the GPs' patients judged themselves to be depressed and that in these patients, the GPs diagnosed depression in only 39% of cases. This low level of correspondence between physician and patient in regard to depression can be accounted for by the finding that first, there is little difference between depressed and non-depressed patients in the manner in which they distinguish themselves in regard to their reason for encounter and that second, depressed patients expressed more somatic (57%) than mental symptoms (20%). A depressive disorder was only reported for 5% of the patients who had judged themselves to be depressed. On the whole, the results have shown that the reasons for seeking treatment expressed by patients had a significant influence on correspondence between the physician and patient: for patients who had been judged by a physician and themselves to be depressed, mental complaints (34%) were more likely to be reported than for patients who had not been diagnosed with depression by their GPs (10%). Additional questions addressed to the physicians revealed that they were more likely to diagnose depression on the basis of the patients' self-ratings and behaviour than to routinely question the patients for symptoms of depression. Hence, the study underlines the need for training in criteria-orientated diagnosis and the application of suitable screening instruments for depressive disorders in general practice.