Apomorphine is a potent dopaminergic agonist that quickly and predictably reverts parkinsonian symptomatology. In 32 patients (18 male) aged 45 to 83 years old (22 with idiopathic parkinsonism and 10 with parkinsonism of other causes), the dopaminergic response to apomorphine after domperidone administration was assessed using the digital skill test and Webster scale. Twenty patients with idiopathic parkinsonism and 1 with parkinsonism of other causes had a positive response to apomorphine. In 44% apomorphine had adverse effects. All patients with idiopathic parkinsonism and the only patient with parkinsonism of other causes with a positive apomorphine test had a good response to levodopa therapy. It is concluded that apomorphine test has a 95% positive predictive value for idiopathic parkinsonism and is a useful diagnostic tool.