DNA techniques were applied to typing a population of renal patients in order to assess the number of discrepancies between this technique and the serological technique. Five patients had been given an incorrect type by serology, and in 22 instances allogenotypes were found where previously there had been a serological blank. DNA typing was also able to determine allogenotypic subtypes that correlated with DR antigens difficult to split by serology and to determine allogenotypic subtypes correlating with DR antigens not known to have a split by serology. Whereas DNA typing provided a result first time of testing on all but 3 patients, the average number of serological testings for each patient was 1.9.