We report a multiple endocrine neoplasia type 1 (MEN1) patient associated with carcinoid syndrome. A 50-year-old woman had parathyroid hyperplasia with primary hyperparathyroidism, a pancreatic tumor and carcinoid tumors in the liver and duodenum. The primary lesion of the carcinoid was probably the bronchus. Direct sequencing analysis revealed a novel missense mutation at codon 342 in exon 7 causing an amino acid change from alanine to proline (A342P) of the MEN1 gene. Loss of heterozygosity (LOH) was also detected in the resected parathyroid tissue. This mutation appeared to play an important role in the tumorigenesis of the endocrine tissues in the present case.