Linear and whorled nevoid hypermelanosis (LWNH) is a reticulate pigmentary disorder with a sporadic occurrence, generally representing a genetic mosaicism. In this case. we describe a two-month-old girl with trisomy 13, who presented with various systemic anomalies such as congenital ventricular septal defect. microcephaly, auricular deformities, flatness of nasal root, overlapping fingers. umbilical hernia, and LWNH. G-banding chromosomal analyses were per-formed on cultured peripheral blood lymphocytes of the patient and the parents. The karyotype of the patient was 47, XX,+13, with no mosaicism. The karyotypes of the parents were normal. To our knowledge, we present the first patient with LWNH in whom full trisomy 13 was confirmed postnatally in cultured peripheral blood lymphocytes.