This study was investigated to compare the performance and digestibility of nutrients in Lori Bakhtiari (LB) and Romanov × Lori Bakhtiari (R×LB) cross bred lambs. In the first trial, 24 animals at the age of 4 months (12 LB and 12 (R×LB) cross bred lambs) were randomly allocated to individual pens in order to determine fattening performance for a period of 90 days. In the second trial, 3 animals at the age of 10 month from each breed were randomly allocated in individual metabolic cages to determine the in vivo digestibility for 7 days after adaptation period. The results showed that there were no significant effect in initial body weight, daily gain, feed conversion ratio and feed efficiency between treatments. LB lambs had significantly (P<0.05) higher feed intake compared to R × LB cross bred lambs. The study showed that there were no significant differences for digestibility of dry matter, protein, ether extract, acid detergent fibre, neutral detergent fibre, phosphorus, calcium, magnesium and iron between the two breeds. In conclusion the results showed that R× LB cross breed had no significance effect on feed digestibility and fattening characteristics of cross breed lambs. The study indicated that cross breeding was successful in term of consuming less feed with no compromise on weight gain.