Chlorotic leaf distortion (CLD) is an unusual disorder of sweet potato caused by a morphologically unique strain of Fusarium lateritium. This study compared 15 isolates of F. lateritium from sweet potato with nine isolates from other hosts for genetic diversity by RAPD analysis and RFLP analysis of the intergenic spacer region and the ITS region of the rDNA. In RAPD analysis, 12 of the sweet potato isolates clustered very closely, nine with similarity of >0·99, and three additional isolates at a similarity of >0·86. This group comprised two pathotypes and included isolates from U.S.A., South America, Asia and Africa. The remaining isolates, comprising three from sweet potato and all isolates from other hosts, showed little similarity with the cluster of sweet potato isolates. RFLP analysis produced similar results, with the 12 isolates that were clustered in RAPD analysis and one additional sweet potato isolate clustered at >0·80 similarity. These data suggest that the sweet potato CLD pathogen is relatively homogeneous and genetically distinct from other strains of F. lateritium. There was relatively little similarity among isolates of F. lateritium from other hosts.