These results show that UK 738 has only a very slight effect on the symptoms of naturally occuring parkinsonism, and it is not as effective as benzhexol. When compared with a dummy in a double blind trial, benzhexol itself is not outstandingly effective.These results are very different from those obtained by May and his colleagues (3, 4) and although their cases were of phenothiazine induced parkinsonism, it is more likely that the discrepancy is due to their lack of control in the trial than to any difference in aetiology.Abstract Teaser