The 3'HVR has been considered as the most useful probe in making the linkage analysis of adult polycystic kidney disease (APKD). We examined three APKD families using this probe. Their polymorphism information was then computed for linkage study using LINKAGE package and computer programme HOMOG for homogeneity test. One family was defined as non PKD 1, because the disease locus was failed to show linkage to the 3'HVR marker. Of the other two families, one can still not be identified as non PKD1, but had distinguishable meiotic recombinations, another was in favour of linkage to 3'HVR and therefore judged to be PKD1. The presence of genetic heterogeneity could significantly reduce the value of linked probe analysis as a tool for gene diagnosis of APKD.