Fifty grasspea populations that were selected based on administrative regions and differentrnaltitude classes were used in tins study. A total of 1199 entries were evaluated for 14 qualitativernand quantitative morphological traits. Oxalyl diamino propanoic acid (ODAP) variationrnwas determined for 150 entries by taking three entries fi'Om each population. Protein contentrnwas detenrriued for the 50 grasspea populations following a standard procedure. TIle phenotypicrnvariations in three enzyme systems: esterase(EST EC 3.1.1.), acid phosphatase (ACP:ECrn3.1.3.2), and aspmiate amino tranferase(AAT:EC 2.6.1.1) was investigated using horizontalrnstarch gel electrophoresis for 10 populations (25 entries per population) selected from therncluster analysis result based on the morphological data.rnMean, coefficient of variations, heritability, genetic advance, cOlTeiation coefficients, clusterrnanalysis, factor analysis and Shannon's diversity index estimate were used to estimate thernmorphological variation.rnANOVA (analysis of variance) result indicated that there was significant variation for therndifferent traits witlrin a population and between populations. The coefficient of variationrnwas large for most traits in Gonder indicating more diversity in this region. Tins was fmiherrnasceliained by Shannon's diversity index where the mean diversity (H' ) was the highestrnin this region (0.65) followed by Tigray region (H' = 0.64). H at population level rangedrnform 0 (monomorphic) to 0.9 (polymorphic) for some traits. The over all mean diversityrnfor Ethiopia was estimated to be H' =0.61.rnChi-square analysis also showed that there was highly significant variation for each traitsrn(seed size, flower colour, leaflet size and pattem of testa). Some variation in altitude groupsrnwas also noted though it was not significant. Analysis of variance for mean ODAP contentrnand protein content showed non- significant differences between populations. However,rnODAP analysis from single plants showed significant variation both with in a populationrnand between populations. Fortunately, four individual plants with low ODAP contentsrnranging from 0.14% to 0.18% (range with in safe level) were obtained from populationsrncollected from different regions indicating the diversity and variation of this trait with inrnpopulation and between regions. These low ODAP lines are obviously considered importantrnfor further breeding program.rnPhenotypic polymOlphism was obselved for the three enzymes. High phenotypic polymOlphismrnwas observed for esterase. There was negative bnt non significant (t= -0.25) associationrnbetween morphological diversity index and mean expected hetrozygosity base on isozymerndata.rnKey words:Lthyrus sativa, grasspea, lathyrism, diversity, morphological characters,rnODAP, protein, isozyme, conselvation.