Aporphine alkaloids constitute one of the largest groups of isoquinolines, with more than 500 structures reported to date. Structures of these alkaloids include aporphines, proaporphines, secoaporphines, oxoaporphines, dehydroaporphines, 7-hydroxyaporphines, aporphine dimers, and aristolactams. They are widely distributed in plants including Annonaceae, Lauraceae, Monimiaceae, Menispermaceae, Hernandiaceae, Ranunculaceae, and others. Many natural aporphinoids have pharmacological activities, including antioxidant, antiplatelet, antitumor, anticonvulsant, antiplasmodial, antineoplastic, antimalarial, antiprotozoal, antipoliovirus, cytotoxic, and antiparkinsonian effects.1,2 These natural products and their synthetic derivatives serve as leads for the development of potential treatments for a variety of diseases.3-6 R-(-)-Apomorphine (1), the semisynthetic7 or total8 synthetic prototypical aporphine, is an R-(-)-10,11-catecholaporphine (chiral at carbon 6a) with dopamine (DA) receptor agonist activity that includes stimulation of locomotor behavioral activity, with application for the treatment of Parkinson's disease.9,10 S-(+)-Bulbocapnine (4) is a naturally occurring aporphinoid11 that has DA receptor antagonist activity that includes reduction of motor activity and induction of catalepsy.12,13 The cytotoxic and antitumor potentialities of natural and synthetic aporphinoids were reviewed recently by Stevigny and co-workers,5 and their structures have been reviewed annually by Bentley.6 However, since the dopaminergic activities of aporphinoids have not been reviewed systematically since 1985,4,5 we now report a review of progress in understanding the structure-activity relationships of naturally occurring and synthetic aporphinoids in 1990-2005, focusing on dopaminergic agents, structurally related to apomorphine (1) and bulbocapnine (4, Figure 1).