A gene library of Xenopus laevis was constructed from embryonic DNA partially digested with restriction endonucleases Hae III and Alu I and joined to the phage lambda Charon 4 cloning vector with EcoRI linkers. Nucleotide sequences from three of the four related vitellogenin genes have been isolated. Two of the genes (called A1 and A2) were isolated in their entirety together with long stretches of flanking sequences. These two closely related vitellogenin genes have lengths of about 21 and 16 kilobases, but both produce a vitellogenin mRNA of 6.3 kilobases.