Machado-Joseph disease (MJD) is a dominant multisystem degeneration found mostly among Azoreans and characterized by the adulthood onset of cerebellar, ocular, pyramidal, extrapyramidal, and/or peripheral signs. MJD has been recorded in many other populations, particularly in the United States and Japan. Using the microsatellite DNA polymorphisms (STRPs) D14S53, D14S55, D14S48, and D14S45, we found significantly positive lod scores in 16 Portuguese kindreds, suggesting that the MJD locus is linked to chromosome 14q in this population. Differences in age-at-onset and many untyped individuals seem to explain the lower lod scores. Using HOMOG, no evidence was found for heterogeneity with the five Japanese families in whom linkage was reported.