Multiple endocrine neoplasia type 1(MEN1) is an autosomal dominant syndrome. Although thymic carcinoid tumor is recognized as a part of MEN1 syndrome but functioning thymic carcinoid tumor as the first presentation of the MEN1 seems to be very rare. In this report, we present a 29-year-old male who developed ectopic Cushing syndrome secondary to thymic carcinoid tumor and was diagnosed as MEN1 syndrome 2 years later. Further evaluation revealed the presence of carcinoid tumor and other MEN 1 manifestations in several other member of family. Genetic evaluation showed presence of a previously reported mutation in exon 10(R527X) of MEN1 gene in these patients. This presentation showed that thymic neuroendocrine tumor could be the first manifestation of the MEN1 syndrome and it might be diagnosed as a dominant manifestation of this syndrome in a family. We suggest biochemical or genetic screening for MEN-1 syndrome for patients with thymic carcinoid.