Hemoglobin Tampa was detected in a 6-year-old male caucasian who is homozygous for this variant hemoglobin. The variant hemoglobin has an electrophoretic mobility between Hb F and Hb S on cellulose acetate (pH 8.5) and a mobility between Hb S and Hb C on citrate agar (pH 6.0). In acid buffer globin chain analysis revealed an abnormal beta chain with a mobility between the beta A and beta S chains, and in alkaline buffer the mobility of the chain was at the beta S position. Structural characterization of the variant beta chain indicates that aspartic acid is replaced with tyrosine at position 79, the site of a previously reported mutation, Asp replaced by Gly (Hb Hsi-Tsou). The clinical histories of the available family members including the homozygous propositus appear to be unremarkable.