Two numerical taxonomic techniques, single linkage cluster analysis (SLCA) and principal components analysis (PCA) were used to study the relationship between Dioscorea cayenensis and D. rotundata cultivars. The study was prompted by the confusion in the taxonomy of the two taxa. Twenty-two cultivars (14 of D. rotundata and 8 of D. cayenensis) were collected and planted under the same environmental conditions for 3 successive years. Altogether, 76 characters, which include morphological, anatomical and ecological characters were observed and coded for analyses. Results from both methods agreed and showed that two groups of taxa exist. The discrimination between groups and description of differences between groups were more strongly marked from the PCA than in the SLCA.