The current study was conducted to investigate the effect of addition green tea and tetracycline hydrochloride or both of them to growing buffalo rations on   digestibility, blood metabolites and animal performance. Twelve buffalo calves of 11-13 months of age weighing 213 ±3.52 kg were divided into 4 groups of 3 animals each. Dried green tea was added to calves in basic diet (control) at levels of 0.5 % (T1), 1 % tetracycline hydrochloride  (T2), and 1 % dried green tea and 1% tetracycline  hydrochloride (T3) for  4 month experimental period . All animals of these groups were fed 80% of their requirements as concentrate mixture while wheat straw and alfalfa hay was given.  The quantity of concentrate mixture was adjusted every month according to change in body weight (NRC, 2001).  The results indicated that dietary supplementation of green tea and tetracycline, or both of them did not significantly (p<0.05) affect on all nutrient digestibility, except EE digestibility was significantly (p<0.05) lower in group T3 than control. No statistically significant differences were observed among the feed supplemented groups for blood proteins, namely albumin and globulin. Buffalos calves fed  rations supplemented with tetracycline in T2 or tetracycline and green tea in T3 decreased significantly (P<0.05) serum total cholesterol as compared with those fed control and green tea rations (163.80 and 166.99 vs. 196.17 and 203.31 respectively).  Also, no significant differences were observed among all treatments for ALT and AST. However, it was noticed that buffalos fed supplemented tetracycline and green tea in T3 tended to be lower by 3.5 % and 7.3 % for ALT and AST respectively than control group. On the other hand, performance of growing calves in terms of average daily gain, total dry matter intake and fed conversion ratio did not affected by supplemented green tea and tetracycline or both of them to rations. From the results of this study it can be concluded that incorporating green tea at a rate of 0.5 % and tetracycline at a rate of 1 %is Insufficient to improve digestibility and performances of growing buffalo, however mixed feed additive from green tea and tetracycline by rate 1% may be suitable for buffalo's calves, which slightly improvements were noticed.