Histological tissue sections of human testicular embryonal carcinoma from 13 patients and of a xenograft tumour in nude mice, as well as cell lines of human embryonal carcinoma, were investigated with eight different lectins to characterize the distribution of glycoconjugates in embryonal carcinoma. In all cases the malignant cells showed binding with Con A, WGA and RCA I conjugates, whereas other lectins were bound to some, but never to all, tumour cells in each group, revealing the heterogeneity of the malignant cells. A polarization of cancer cells was shown particularly with WGA and RCA I labelling, which was most intense on the luminal borders of the carcinoma cells, where pseudotubular structures were formed. The sugar staining properties were retained in cell culture and in the xenograft tumour. Regardless of the germ cell origin, embryonal carcinoma cells differed from normal germ cells. The distribution of glycoconjugates was also different from that of testicular carcinoma-in-situ germ cells, which share morphological features and the pattern of glycosylation with seminoma cells. However, the similarities in lectin binding pattern of seminomas and embryonal carcinomas suggest the close relationship between the two types of testicular malignancy, without excluding the possibility that embryonal carcinomas were derived from seminomas. Although lectins seem to be less important for differential diagnostic use in testicular cancer, our findings showed the usefulness of lectin histochemistry for characterization of embryonal carcinoma.