Neuroleptic malignant-like syndrome (NMLS) occurred after rapid switch from bromocriptine to pergolide in a Parkinsonian patient. Although the underlying mechanisms are as yet obscure, we hypothesize that differences in dopamine receptor affinities between bromocriptine and pergolide may be involved. Long-term treatment with bromocriptine may thus have induced plastic changes in intracellular signal processing in the nigrostriatal system, which resulted in reduced dopaminergic efficacy of pergolide. We recommend vigilant outpatient supervision during performance of rapid switchover from one dopamine agonist to another in advanced Parkinson's disease or in subjects with predisposing factors for onset of a neuroleptic malignant syndrome.