42 persons which commited crime sexual actions were examined in terms of clinical and neurochemical investigations. The sexual behaviours of 31 patients from this group were associated with sexual inclination pathology--with paraphilia. The patients were divided into 2 groups namely with compulsive form of paraphilia (13 individuals) and without compulsive disturbances (18 patients). Both free and conjugated forms of norepinephrine (NA), dopamine (DA), dihyroxyphenylalanine (DOPA) and dihyroxyphenylacetic acid (DOPAC) were measured in serum and daily urine as well as serotonin concentration was estimated in blood plasma and platelets. The rate of 3H-serotonin uptake into platelets (Vmax) was also investigated. It was determined that Vmax, free and especially conjugated forms of NA, DA, DOPAC levels were significantly higher in patients with compulsive forms of paraphilia. It was supposed that monoamine mechanisms may be operated in psychopathological variations of the crime sexual behaviour.