Fifty-five populations of root-knot nematodes were established from individual egg massesrncollected from different parts of the country. Perineal pattern, stylet length, chromosome numberrnand esterase isozyme phenotypes of these populations were investigated. Three species were Chromosome number was counted in the germinal zone of the ovary. High intra-specific andrnintra-population variability was observed in populations of lvf incognita and lvf ethiopica. In bothrnspecies diploid, 36-38 and hypotriploid, 40-46 chromosome numbers were counted. I'd javanicarndid not show much variability with a hypotriploid chromosome number of 40-46. Four esterase isozyme phenotypes were identified in the populations of the three species. !vi.rnincognita and lvf javallica populations had the I1 and J3 phenotypes, respectively, while !vIrnethiopica populations had two phenotypes, E3 and E2. E3 was found to be species-specific andrnpotentially useful for diagnosis. Due to its high incidence, lvf ethiopica is considered to be anrnimportant parasite.rnidentified: I'vieloidogyne incognita (58.2%), lvf javallica (16.4%) and lvf ethiopica (25.4%) basedrnmainly on perineal pattern and esterase isozyme phenotypes. Populations of 114. incognita.rnexhibited extensive variation in perineal pattern, whereas less variability was observed inrnpopulations of lyi. javanica J!Q.Q.lvf ethiopica. Stylet length of populations of !vI javanica and !vi.rnethiopica obtained from enset was found to be significantly larger (P = 0.05) than the otherrnpopulations. This is thought to be a possible form of an adaptation.