The isolation and characterization of a Xenopus laevis albumin cDNA clone, pUN18, is described. This clone was identified as a X. laevis albumin cDNA clone by hybridization-mRNA selection-translation and by other techniques. The clone was used in hybridizations to determine the effect of estrogen on albumin synthesis in livers of male X. laevis. We find that albumin mRNA levels remain relatively constant during the massive induction of vitellogenin mRNA synthesis and vitellogenin secretion which follow administration of estrogen to male X. laevis.