Berseem is a conventional and cheapest green forage distributed all over the world. It is a good source of fiber and high nutritive value thus, it used as adlibitum feed for young growing rabbit. Additionally, rabbit is characterized by hind gut fermenter animals through its caecal microbial fermentation as well as rabbit has strong accommodation to high level of fiber diets that increasing the digestive efficiency moreover, it help the rabbits in microbial digestion and production of an energetic substance (volatile fatty acids &high quality proteins). Therefore, this study was applied for examining the outcome of berseem replacement as a cheap green forage by expensive commercial pellets feed in young growing rabbit; by means growth performance, carcass trait, histomorphometric, hematological profiles and behavioural changes. Twenty-four growing male rabbits (white New-Zealand breed) were used and classified into three different groups; two groups of them were supplemented with different two levels of Egyptian green berseem 50% with 50% pellets and berseem 90% with 10% pellets as well as the third group feeds on 100% commercial pellets. The diet was offered to rabbit by rate 4% of their body weight on dry matter basis daily. The study lasted for four weeks. Results showed that, the body weight and weight gain of rabbits were affected by berseem treatments. Moreover, using forage as green Egyptian berseem in rabbit diet with concentrates had a significant effect on feeding and exploration behaviour and a significant increase in total blood protein, globulin, albumin and decrease in A/G ratio. Furthermore, rabbits fed with the mixed diets had lower total cholesterol than those fed with control and they had higher HDL than control group in most blood parameters considered; the values are similar in all groups. Furthermore, there are a significant increase the length of duodenum and ileum but carcass traits were not affected. As well as increase the height of the intestinal villi, depth of crypt and increase thickness of muscular layer of intestine in rabbits fed on berssem groups.