We tested a novel preparation of sublingual apomorphine hydrochloride (APO) in 10 patients with advanced Parkinson's disease complicated by motor fluctuations and dyskinesias. After dose titration, patients underwent a blinded comparison of APO versus placebo, and an unblinded comparison of APO versus optimally dosed carbidopa/levodopa using timed tapping and walking paradigms. APO was significantly better than placebo in both measures: Tapping speed was 30.8% faster than with placebo (p< .0005), and ambulation speed was 45.2% faster than with placebo (p< .05). Ambulation speed with APO was also 15.9% faster than that with optimal doses of carbidopa/levodopa (p< .05). The latency to onset of clinical improvement with each APO dose was 10 to 40 minutes, and the duration of effect was 60 to 130 minutes. Adverse events included nausea, orthostatic hypotension, and disagreeable taste in the patient's mouth. Aside from the bitter taste, all other side effects resolved with continued use and did not limit dosing in any case. We feel that the good short-term efficacy and tolerability demonstrated in this study warrant further study of this new preparation, as there are several potential advantages of sublingual administration compared with traditional APO preparations.