We examined the molecular basis for rabbit C8 alpha-gamma deficiency (C8D) using human C8 cDNA probes. Sequential probing of normal rabbit poly(A)+RNA revealed messages of 2.1, 1.9, and 0.8 kb for alpha, beta, and gamma, respectively. Corresponding analysis of C8D rabbit poly(A)+RNA identified messages for alpha and gamma of the same size and amounts as normal rabbits. Thus, C8 alpha-gamma deficiency in the rabbit appears to be the result of a translational rather than a transcriptional defect.