In a previous investigation of whether reduced dopamine-beta-hydroxylase (DBH) might play a role in schizophrenia, we studied the effects of DBH inhibition for a few hours in normal subjects. This initial study showed positive effects, i.e., unusual subjective psychological reports confirmed by psychiatric rating scales, in subjects given the DBH inhibitor fusaric acid. The present study attempted to replicate these findings using a more detailed battery of tests and an additional control situation. Each subject underwent the following four treatment conditions at 1-week intervals: fusaric acid plus L-dopa; L-dopa alone; d-amphetamine; placebo. The present results did not confirm those of the first study. A few interesting results were found that were chiefly attributable to amphetamine effects. No effect could be definitely attributed to fusaric acid.