Germline mutations in the MEN1 gene are well documented as the genetic cause of multiple endocrine neoplasia type 1 (MEN1). In this study, we performed genetic analysis by direct MEN1 gene mutation analysis on a Chinese MEN1 family. The two patients in this family were diagnosed as MEN1 by the typical clinical findings of parathyroidoma, insulinoma and pituitary adenoma. The coding sequences, including 9 coding exons and exon/intron boundaries of the MEN1 gene were amplified by polymerase chain reaction (PCR) and subjected to direct sequencing. Sequence analysis showed a same novel insertion mutation in exon 3 (c.433_434ins CTTC) in both patients, resulting in an open reading frames shift and produced a premature termination codon. None of the other family members had this insert mutation. In conclusion, we add a new mutation of MEN1 gene in Chinese patients with MEN1, and it would be useful for the diagnosis of the disease.