We present a series of six consecutive Parkinson's disease patients undergoing posteroventral pallidotomy (PVP), who received an apomorphine injection after thermolesioning the posteroventral region of the internal globus pallidus (GPi) to evaluate the effect of the lesion on drug-induced dykinesias and therefore to proceed with further lesions or to conclude the surgery. Five of six patients failed to present dykinesias or did so to a significantly lesser degree (F [2, 10] 42.6; p < 0.0001) so that surgery was concluded. One patient continued having contralateral dyskinesia despite an improvement in rigidity and bradykinesia, therefore, a new track was performed followed by a new lesion. No differences were found between intrasurgical and 1-month postoperative apomorphine test values. This report indicates that the use of an apomorphine test after thermolesioning may provide a reliable tool to check lesion efficacy on dyskinesia. The development of techniques that provide additional clinical information to the electrophysiological recording could help improve the outcome of patients undergoing pallidotomy.