Cotyledons of several collections of each taxon of Cucumis africanus Lindley f., C. anguria L. var. anguria, C. anguria var. longipes Meeuse, C. dipsaceus Ehrenb. ex Spach, C. metuliferus E. Mey ex Schrad., C. myriocarpus Naud., C. zeyheri Sond. (2x, 4x), and C. melo L. were surveyed using horizontal starch gel electrophoresis to characterize interspecific and intra-specific variation and to furnish preliminary phylogenetic information with regard to the cross-compatible group of wild African Cucumis species. Eight enzyme systems were studied: shikimate dehydrogenase, triose-phosphate isomerase, glutamic-pyruvic transaminase, glucose-phosphate isomerase, phosphogluconate dehydrogenase, isocitrate dehydrogenase, peptidase with phenylalanyl-L-proline, and phosphoglucomutase. All enzymes were polymorphic. Although C. anguria var. anguria accessions from Brazil and Ethiopia were similar, zymograms of C. anguria var. longipes were more similar to the C. melo collections. Results from var. anguria and var. longipes support previous data with regard to their varietal nature. The relative similarity among patterns of C. anguria var. longipes, C. metuliferus, and C. myriocarpus suggests a closer phylogenetic relationship than had previously been proposed. Isozyme similarities between C. anguria var. anguria, C. africanus, and C. dipsaceus suggest some phylogenetic affinities.