Five cases of parkinsonism with athymhormia observed in a single family are reported. Death caused by central respiratory disorders occurred after 6 to 8 years of progressive course. In 2 cases with autopsy, there was a severe neuronal loss predominant in the substantia nigra. Other brain stem nuclei (locus coeruleus, dorsal motor nucleus of the vagus nerve, nucleus of the tractus solitarius) were involved, as well as the striatum, pallidum and frontal cortex. No Lewy body was seen. In the surviving patient, positron emission tomography demonstrated, 4 years after the onset, a bilateral frontal hypometabolism. This disease is a rare variety of familial parkinsonism of dominant inheritance, already reported in 2 Canadian families by Perry et al. (1975) and Purdy et al. (1978) and in a family of West Virginia by Roy et al. (1988). The respiratory disorders can be explained by the involvement of the dorsal medullary nuclei. The peculiar neuropsychological disorder and motor slowing are best accounted for by the functional impairment of both motor and limbic striato-pallido-thalamo-frontal loops.