Cephalometric studies of adult Mexican-Americans are incomplete. The purpose of this study was to evaluate whether significant cephalometric differences exist between adult Mexican-American, black American, and white patients. Lateral cephalometric radiographs were taken of 48 Mexican-American adults (23 men, 25 women). All subjects met the following criteria: parents, grandparents, or great-grandparents were born in Mexico; 18 to 50 years of age; Class I occlusion with minor or no crowding; good facial balance; no significant medical history or history of facial trauma; no previous orthodontic treatment or maxillofacial surgery. Twenty-five cephalometric measurements were analyzed. Significant racial and sexual differences were found in the following areas: skeletal measurement (SNA, ANB, PO-N perpendicular, Co-A, Co-Gn, ANS-Me, MP-FH, MP-SN); dental measurement (U1-A perpendicular, L1-APo, U1-L1, IMPA); soft tissue measurement (NLA, FCA, UFH (pu), ULL). Orthodontists and oral surgeons will find the cephalometric values of help in the diagnosis and treatment planning of potential orthognathic surgery patients.