To identify symptomatological characteristics of solvent psychosis, 9 cases of chronic thinner intoxication with psychitaric evidence during the abstinent period are studied. The results were as follows: 1) During intoxication, 7 cases had visual hallucinations and 3 cases had auditory hallucinations. 2) Eight cases had irritabilities or mood disturbances without thinner intoxication. 3) Four cases had convulsions or delirium which were observed only in the withdrawal period, suggesting that these symptoms might be withdrawal signs of thinner dependence. 4) Six cases had Schneiderian first rank symptoms such as auditory hallucinations (i.e. voices commenting, voices arguing), delusions of control (withdrawal of thought, thought insertion, influence of thought) and delusional perception. Hallucinations that appeared in acute intoxication with thinner in 5 of the 6 cases, were second rank symptoms. Five of the 6 cases did not show negative symptoms (i.e. blunting of thought) and they could maintain good emotional contact with other. Symptoms of these 5 cases were different from those of schizophrenia or the flashback phenomenon of thinner dependence. These cases suggest that Schneiderian first rank symptoms and maintenance of emotional contact are important for diagnosis of volatile solvent psychosis.