148 chronic schizophrenics admitted between 1938 and 1961 had previously been followed up. In 1972, they were re-examined, on the average 10 years after the first follow-up. 44 belonged to a series of patients studied between 1955 and 1957 with a battery of conditional reflex tests. The patients belonging to the experimental series were retested with word associations. From an experimental point of view the patients performed better over the prolonged observation period. The clinical state also showed improvement. A comparison of the chronic hospital population during 1955–57 and 1972–74 suggests that the new chronics present much less of the severe schizophrenic deterioration than the old ones. They also have remarkably better verbal functions. These changes are assumed to be mainly due to drug treatment. The beneficial effects of drugs appear to come mainly within the first 2 years.