Abstract. In the partial system of diallele crosses by Savchenko (1973) eleven mid-late maize lines which belong to two genetically different groups – SSS and Lancaster are involved for study of Combining Ability of grain yield. The hybrids obtained from these lines are tested in two years – 2008 and 2009. The highest GCA from the studied lines have 215/3-1-1(C ), 45/1-1-2(C ) and 7/1-2-1(C ) from SSS group and 220/2-1-1(C ) and 178/2-2-1(C ) from Lancaster, which are 2 1 3 2 2 recommended in the breeding programs for creating high-yield synthetics. With highest SCA are the lines 9/1-1-1(C ), 45/1-1-2(C ), and 119/1-1(C ) from SSS 2 1 3 group and 220/2-1-1(C ), 178/2-2-1(C ) and 88/1-2-1 (C ) from Lancaster, which could be used in the heterosis breeding for developing high productive hybrid 2 2 3 combinations.