We have isolated the Xenopus homolog (Xint-1) of the mouse protooncogene int-1 from a neurula stage 17 cDNA library. The deduced protein sequence of Xint-1 includes 371 amino acids. The Xint-1 protein is more similar to the mammalian int-1 product (69%), than to the Drosophila counterpart of int-1, wingless (50%). Xint-1 shares several characteristics of secreted proteins with the other int-1 homologs: it has a hydrophobic leader, multiple conserved potential N-linked glycosylation sites and is rich in cysteine residues. All 23 cysteines are conserved in the three proteins. Xint-1 is transiently expressed during the neurula stages of early Xenopus development.