Dopaminergic treatment in dementia with Lewy bodies (DLB) requires balancing risk of worsened psychosis and potential motor benefit. We assessed the effects of increased dopaminergic medication on psychosis and motor function in DLB. We studied 19 subjects fulfilling probable DLB Consensus criteria before and after increased dopaminergic medications. Standard clinical measures included: Thought Disorder score from the Unified Parkinson's disease Rating Scale (UPDRS) Part I, total motor score (UPDRS Part III), and Hoehn-Yahr (H&Y) stage. Motor benefit defined as >10% improvement over baseline UPDRS Part III score, occurred in only one-third of subjects. In this group, worsened hallucinations or psychosis developed in one-third. Considering motor benefit without exacerbation of psychosis as our aim, only 4 DLB subjects (22%) achieved this goal. Our results suggest that dopaminergic medications have limited benefit in DLB because of the low likelihood of motor improvement and the risk of psychosis exacerbation.