SRY-related genes are known as Sox (Sry-box) genes. Two Sox cDNAs from Xenopus oocytes were analyzed. The deduced product of the Xenopus Sox gene (xSox-11) consisted of the standard domains of an HMG box, glycine/alanine-rich region and glutamic acid/aspartic acid-rich region and may be involved in the control of transcription. The other Sox gene (xSox-11-D) had a deletion of 262 nucleotides at one end of the HMG box in the xSox-11 cDNA. The deletion resulted in a frame-shift and in variations in base pair composition and the length of the trinucleotide repeat in the C-terminal coding region. The amino acid sequence of the C-terminal domain encoded by xSox-II-D was highly basic and might be involved, together with the HMG box, in the binding to DNA.