Representatives of the Euphorbiaceae s.l. in the flora of Egypt are notoriously difficult to identify with any degree of certainty, especially when using the manually constructed keys currently available for them. Such keys are based largely on single characters separating alternative entries of the same couplet which may vary considerably in individual plants of the same species. To benefit from the versatility and advantages of computer programs designed for key construction, two data matrices were constructed to accommodate comparative variation in the features of vegetative and floral morphology of three succulent Euphorbia species and 45 non-succulent species of the eight genera representing the Euphorbiaceae s.s. and the Phyllanthaceae in the flora of Egypt. Each matrix was subjected to analysis using the DELTA package of computer programs to generate a key to the species, accompanied by detailed and item descriptions of individual species in terms of the recorded characters for confirmation the results obtained by the user. Both keys are a marked improvement over their previous manually constructed counterparts.