In a study in 97 patients on the occurrence of disturbances of liver functions by use of long acting neuroleptic drugs (fluphenazine decanoate, flupenthixol decanoate and fluspirilene) no indications were found that these agents, even in relatively high dosages, are hepatotoxic. Furthermore, in 40% of the patients slight disturbances were found, which nevertheless, were not specific in nature, and mostly concerned the turbidity tests. In spite of these findings a regular control (for instances, once a year) of the liver functions in patients with long acting neuroleptic drugs seems to be called for.