This study aimed at describing preoperative psychiatric morbidity in a consecutive series of 70 epilepsy patients who were surgically treated and to analyze postoperative psychiatric morbidity and predisposing factors. Nonorganic (DSM-III-R) and organic (Lindqvist-Malmgren diagnostic system) psychiatric morbidity was prospectively assessed preoperatively and during the first two postoperative years. At presurgical evaluation 44.3% of the patients had a psychiatric diagnosis (nonorganic in 14.3%, organic in 38.6%). The most common nonorganic diagnosis was major depression; the most common organic diagnosis was Astheno-Emotional disorder (AE disorder). During the first two postoperative years 68.1% of the patients received some psychiatric diagnosis. The most common nonorganic diagnoses were anxiety and depressive disorders (AD disorders) in 36.2%; the most common organic diagnosis was AE disorder in 52.2%. Patients with a preoperative history of AD disorders or AE disorder had a significantly higher risk of postoperative AD disorders (P < 0.01 and P < 0.001 respectively). Laterality, type of resection, histopathological diagnosis, or outcome were not significantly related to postoperative psychiatric morbidity. The importance of psychiatric assessment, including organic psychiatric disorders, is emphasized.