An autosomal recessive form of juvenile Parkinsonism (AR-JP) (MIM 600116) is a levodopa-responsive Parkinsonism whose pathological finding is a highly selective degeneration of dopaminergic neurons in the zona compacta of the substantia nigra. By linkage analysis of diallelic polymorphism of the Mn-superoxide dismutase gene (SOD2), we found a family with AR-JP showing perfect segregation of the disease with the SOD2 locus. By extending the linkage analysis to 13 families with AR-JP, we discovered strong evidence for the localization of the AR-JP gene at chromosome 6q25.2-27, including the SOD2 locus, with the maximal cumulative pairwise LOD scores of 7.26 and 7.71 at D6S305 (theta = .03) and D6S253 (theta = .02), respectively. Observation of obligate recombination events, as well as multipoint linkage analysis, placed the AR-JP gene in a 17-cM interval between D6S437 and D6S264. Delineation of the AR-JP gene will be an important step toward our understanding of the molecular mechanism underlying selective degeneration of the nigral neurons.