Mutations in the parkin gene are a common cause of autosomal recessive, juvenile or early onset parkinsonism (PARK2). In this report, we use RT-PCR to detect compound heterozygous deletions of the parkin gene in fibroblasts from two cases of middle age-onset familial parkinsonism with lower extremities-dominant resting tremor and mild cogwheel rigidity. Although exonic amplification of the parkin gene showed a deletional mutation of exon 3-4, their family histories suggested that the deletional mutations were a compound heterozygous abnormality of discrete origin. Immunoblotting demonstrated that abundant Parkin protein was expressed in fibroblasts, but little expression was detected in lymphocytes. RT-PCR using RNA isolated from the patients' fibroblasts indicated a parkin mutation in this family that consisted of compound heterozygous deletions (del exon3-4/del exon3-5). These results suggest that RT-PCR using the patients' fibroblasts may be helpful for the detection of compound heterozygous abnormalities in the parkin gene.