Merkel cell carcinoma (MCC) is a malignant tumor of the skin with a well-established neuroendocrine phenotype but an unknown histogenetic origin. Cytogenetic and molecular studies have shown evidence for genetic changes on the distal portion of chromosome 1p in different tumors with well-established neuroendocrine origins, specifically neuroblastomas, malignant melanomas, and pheochromocytomas. Involvement of chromosome 1 in MCC recently has been demonstrated by cytogenetic analysis and analysis of loss of heterozygosity (LOH) in metastatic tumor tissue. We performed analysis of LOH of the distal portion of chromosome 1p in paraffin material of 10 primary MCCs after tissue microdissection, using the polymorphic markers D1S160, D1S243, D1S468, D1S1646, and D1S1598. Seven of 10 analyzed MCCs shared a distal deletion involving 1p35-36. None of the cases showed 1p involvement proximal to 1p35. The findings are similar to those described for malignant melanoma, pheochromocytoma, and neuroblastoma, tumors known to originate from neural crest cells. In conjunction with previous cytogenetic data, we conclude that Merkel cell carcinogenesis shares pathogenetic mechanisms with other neoplasms of neural crest derivation.