The rate of detection of depressed patients by general practitioners (GPs) is generally reported to be lower than 50%, with some studies giving a value as low as 14%. In addition, GPs tend to overdiagnose anxiety and underdiagnose depression. Patients are not necessarily aware of the psychological nature of the disorder and only one-fifth list psychological complaints as the reason for contact. We collected information on the prescription and consumption of drugs in order to assess the influence of recognition of depression by GPs and of other factors on the treatment received by patients. Our results, which are particularly important in the context of current discussions on the cost of mental healthcare treatments, indicate not only a need for GPs to improve their identification rates but also a need to make patients more aware of the nature of their psychological diagnoses. When spontaneous psychological complaints are presented, the identification rate increases very substantially, and when patients are well aware of their conditions, compliance increases. It is clear from our results that greater specific recognition of psychiatric patients accompanied by the prescription of a specific treatment would not substantially alter the direct costs of drug prescription. On the contrary, it would very probably lower many costs, since the proportion of specific treatment given to properly identified patients is very low at present.