Parkin mutations have been associated with an autosomal recessive-juvenile parkinsonism, but it is unclear how common such patients are in a US based clinic population. In this study, we screened for parkin gene mutations in a clinic-based series of 27 consecutive patients in the US with typical parkinsonism beginning before the age of 50 years. Two patients began the disease before the age of 30 years. Among the 27 patients screened, only one patient, whose disease began at the age of 24 years, was found to harbor a parkin mutation (a 40 bp deletion in exon 3). In addition, we also identified four new polymorphisms in the open reading frames of the parkin gene in this population. Our results suggest parkinsonism due to mutations in the parkin gene is extremely rare in the US population when the disease begins over the age of 30.