Xenopus laevis larval thymocytes and splenocytes were examined for the presence of Ig determinants by an indirect immunofluorescence technique, using rabbit antiserum to deglycosylated Xenopus immunoglobulins. Thymocytes had no detectable surface membrane Ig, while Ig determinants were identified on the surface of a large percentage of the lymphocytes from the spleen. The positive fluorescent staining that one obtains on the surface of thymocytes using antisera to intact Ig's is due to antibody molecules directed to the carbohydrate determinants of the Ig's which cross-react with thymocytes' surface carbohydrate determinants.