Abstract: The present study was conducted to evaluate water melon (Citrullus Lanatus) seed cake as a possible protein supplement for growing Iamb in comparison to groundnut cake. Graded proportion of water melon seed cake (WMSC) (0, 25, 50, 75, 100%) which replace groundnut cake (GNC) were incorporated in five diets iso-caloric, iso-nitrogenous diets for lamb. Diet A contained 0% proportion of MWSC, diet B, C, D and E contained 25, 50, 75 and 100% WMSC proportions, respectively. Forty five yearling male lambs of Sudan desert sheep ecotype Kabashi with average body weight of 31.5kg were used for feeding trial. There was a significant (P < 0.01) linear decrease in feed intake and average daily live weight gain with increasing WMSC level in the diet, but dietary treatments had no significant effect on feed conversion efficiency and final body weight. However, lambs fed diet A (0% WMSC) was found to be superior over the other treatment groups in previous parameters.