Isozyme markers were used to determine genetic relatedness between sixty cultivated Hevea clones originating from the Wickham collection. The mean observed heterozygosity for the clones was 0.0567. A dendrogram representing phenetic relationships among the clones in the study was constructed using the unweighted pair-group method with arithmetic averaging. Considerable genetic diversity was observed (mean genetic similarity = 0.754) despite the fact that the gene pool was derived from a small number of plants originally sourced from a single collection area in Brazil. Principal component analysis of the genetic diversity among the sixty clones showed that PR clones and PB clones formed distictly different clusters. On the other hand, the RRIM clones were evently distributed, reflecting the selection of RRIM clones from a generally wider genetic base. Isozyme polymorphism was evaluated as a tool for clonal identification and verification among source bushes (from which buds for vegetative propagation are generally obtained). A panel of seven isozymes identified fiftytwo out of sixty commercially planted clones outright, while four pairs of clones shared common zymograms. A 0.2;probability of identification error was estimated for the chance occurrence that a rogue plant would have an isozyme profile identical to that of the purported clone. Isozymes were also used to validate 24 clonal progenies derived from hand-pollination. Genotypes of 23 clones were found to be consistent with those of their assigned pedigrees. The exception was RRIM 936 which had some alleles that were absent in either of the purported parents.