Four members from three generations of a family of Italian descent were found to have hemoglobin (Hb) Lepore trait. The four affected members were only slightly anemic, yet had definite hypochromic and microcytic red blood cells (RBC). Electrophoresis of hemoglobin demonstrated an abnormal non-sickling hemoglobin of 11% to 14% concentration that migrated like Hb S at alkaline pH. Amino acid analysis confirmed the identity of the abnormal component as Hb Lepore; the non-alpha chain was a fused delta-beta-chain with a crossover between residues 87 and 116. Hemoglobin Lepore trait should be considered in any patients with clinical and laboratory findings consistent with beta-thalassemia trait and with a 10% to 15% concentration of an abnormal nonsickling hemoglobin that migrates like Hb S.