Globin chain synthesis was studied in vitro with reticulocytes from a patient heterozygous for Hb Abraham Lincoln, an unstable beta chain variant. Synthesis of α-chains by the reticulocytes exceeded total β-chain synthesis, and a substantial fraction (about 16%) of radioactivity incorporated into globin was recovered from the cells as uncombined α subunits. In a time-course study, the ratio of α : β-chain specific activity was found to increase progressively in a nearly linear manner, suggesting that a fraction of newly synthesized β-chains had undergone rapid destruction. The specific activity of the abnormal β-chain was nearly three times that of βA. The rate of synthesis of the β-chain of Hb Abraham Lincoln appeared to be approximately half that of the β-chain of Hb A.