In 57 patients with psicovegetative disorders and abnormal MMPI, abnormality in MMPI scales indicating hypochondriasis, hysteria, gender deviant, paranoia, psychastenia, schizophrenia, hypomania or introversion was accompanied by increased plasma catecholamine levels and/or responses to hypoglycemia or by an increased cardiovascular reactivity. A high depression scale was associated with lower plasma catecholamine levels. Blunted plasma growth hormone responses to hypoglycemia were found in abnormal hypomania scale, and augmented responses of plasma cortisol in abnormal hysteria or schizophrenia scales. Paranoia and hypomania traits correlated with absence of morning-evening differences in blood cortisol levels. Electrodermal responses compatible with increased sympathetic activity correlated with high hysteria, gender, paranoia, schizophrenia or hypomania MMPI scales. This study indicates that most psychopathological traits in MMPI are accompanied by humoral and/or electrophysiological signs of abnormality of the autonomic nervous system.