Evaluation of paternity (alleged father, mother, and child) can range from a straightforward resolution to a complex problem that can-not be resolved without family studies. We present a case of disputed paternity in which tests for crossreactive groups (CREGs) and antigen subtypes (splits) within the human leukocyte antigen (HLA) system could not be used confidendy to prove or disprove paternity. Further analysis, red cell enzyme tests, enabled a final verdict and confirmed the current reliability of HLA antisera defining splits.