Angiostrongylosis is a recently recognized disease of man. The causal agent, Angiostrongylus cantonensis, is a metastrongyloid nematode of rats, which develops in the brain before taking up its final location in pulmonary arteries. This parasite migrates to the brain of man where it will develop, although there is no evidence it will mature. The presence of A. cantonensis in the central nervous system causes eosinophilic meningoencephalitis of man in the Pacific and southeast Asia. Much credit for unravelling the involved transmission and clinical nature of human angiostrongylosis must go to Alicata of the University of Hawaii and Leon Rosen of the National Institute of Health and their co-workers who have, in a few years of intensive research in the south Pacific, provided us with a most satisfactory picture of this strange disease. Rival hypotheses, differences in approach, and the foundation laid by Mackerras and Sandars in Australia, were unusually effective in pinpointing the causal agent and its epidemiology and control.