The authors studied a prolonged (3--5 years) use of leponex in 23 patients with the most progressive forms of schizophrenia (hebephrenic, paranoid and close to them attack-like). The study included the influence on the frequency and duration of relapses, on the dynamics of the so-called productive and negative disorders and social adaptation. The achieved data indicate that leponex possesses certain advantages compared to other neuroleptical drugs in prolonged maintenance therapy. Leponex has a rather "universal" psychopharmacological effect which includes a capability of arresting acute psychoses, exerts a psychoregulating influence on the general behaviour, contacts and socio-working adaptation, distinctly alleviates the clinical signs and frequency of relapses. Due to the absence of motor disturbances and minimum of other side-effects leponex is quite convenient for prolonged use and promotes a higher quality of remissions.