Three experiments were conducted to evaluate the growth performance and egg production parameters of ISA-BROWN (ISA-B) growing pullets and laying birds fed Herbomethionine and DL-Methionine in their diets. In the first experiment, 234 nine weeks old growing pullets with an average initial weight of 625g were allotted to six dietary treatment groups. There were 39 birds per treatment made up of three replicates of thirteen birds each. In the second and third experiments, 216 laying birds selected from birds used in experiment 1 with an average initial weight of 1500g and 1610g respectively were allotted to six dietary treatment groups of 36 birds replicated three times with 12 birds each. Treatment 1 had 0.10% DL-Methionine, no Herbomethionine, Treatment 2 had 0.10% Herbomethionine, no DL-Methionine, Treatment 3 had 0.10% each of DL-Methionine and Herbomethionine, Treatment 4 had 0.30% DL-Methionine, no Herbomethionine, Treatment 5 had 0.30% Herbomethionine, no DL-Methionine, Treatment 6 had 0.15% of DL-Methionine and 0.15% Herbomethionine. The results of experiment one showed that birds fed DL-Methionine and Herbomethionine at 0.30% performed significantly (P<0.05) better than all other treatments in weight gain (790g and 779g), feed intake (7.34kg and 7.26kg) and feed conversion ratio (8.61 and 9.92) respectively. No significant (P>0.05) difference was observed in mortality. Results of experiments 2 and 3 showed that treatment 6 (birds fed diet with 0.15% of DL-Methionine and 0.15% Herbomethionine methiorep) supplementations performed significantly (P<0.05) better in egg number (82) compared with treatment 2 (birds fed diet with 0.10% Herbomethionine) supplementations. Highest percent hen-day egg production was recorded in T6 (80) than T1 (69) and T2 (65). Dietary treatments had significant (P<0.05) effects on egg shell weight, egg shell thickness, albumen weight and yolk diameter. The Haugh unit was not significantly (P>0.05) affected by dietary treatments. There were significant (P<0.05) differences in hematological parameters such as packed cell volume, hemoglobin count and total proteins. It was concluded that herbomethionine supplemented at 0.30% was found to be as effective as 0.30% DL-methionine in the grower study whereas in the layer study, herbomethionine supplemented at 0.15% plus DL-methionine supplemented at 0.15% gave the best performance in egg production and egg quality.