Technical Abstract: Isozyme variation was studied in 161 accessions of pineapple including four species of Ananas and one of Pseudananas. Six enzyme systems (ADH, GPI, PGM, SKDH, TPI, UGPP) involving seven putative loci revealed 35 electromorphs . Considerable variation exists within and between species of Ananas. Sixty-six distinct zymotypes were identified . Multivariate analyses of isozyme variation indicated that A. comosus contains five genetically diverse groups that do not match perfectly with the traditional varietal groups. Isozyme evidence also suggests that A. erectifolius is a conspecific variant of A. comosus, and that among other wild species, A. ananassoides is more closely related to A. comosus than A. bracteatus. Pseudananas is genetically distinct from all species ofAnanas. It is evident from our study that differentiation among the species of Ananas may be due to ecological isolation rather than genetic divergence with breeding barriers and therefore may represent a species complex .