This study is conducted in order to evaluate the fattening features of native and foreign breeds and their cross breeds in sheep improvement studies conducted in Turkey. Many culture breeds were imported to investigate the lamb production and carcass quality in Turkey. These breeds were both raised as pure breed and used in crossbreeding studies with some of the native breeds. A large number of researches have been conducted to determine the fattening performance of native and culture breeds and their cross breeds. Properties of daily weight gain, feed conversion ratio and dressing percentage were evaluated on the basis of proportional gene contribution and genetic groups belonging to the breeds and cross-breds in the studies. On the basis of genetic groups, crossbreds of native breeds with Merino and French breeds, cross-breds of native breeds inter se and with German Mutton Merino, British Mutton breeds and German Blackhead Mutton were found high (P<0,05) in terms of daily weight gain. In improving feed conversion ratio, utilization opportunities for some foreign breeds were limited. On the basis of proportional gene contributions, increase of the contributions of Kivircik, Karayaka and Morkaraman genes caused decrease in daily weight gain. On the basis of dressing percentage, a statistically significant difference (P>0,05) was not found in both analysis. In this study, it is concluded that, in terms of increasing daily weight gain, while cross-breds of native breeds with Merino and French Mutton breeds could provide advantage, cross-breds of native breeds with German Mutton Merino, British Mutton breeds and German Blackhead Mutton could only provide a partial advantage. In improving dressing percentage, since a significant advantage was not observed in cross-breds of native breeds inter se and with culture breeds, it is concluded that studies do not have much benefit on the property.