In our testing program of early maize for export to areas with cool and limited period of vegetation the greatest performance has been obtained in single cross hybrids realized in heterotic patterns Reid Iodent x BSSS-B37 and Reid Iodent x Euroflint. These three groups of germplasm, considered to be more successful at present, being used in constructing breeding starts. The recycling of superior commercial inbred lines is a common method for improvement of weakness agronomic valuable traits, including general combining ability. Among Reid Iodent heterotic group an essential genetic progress has resulted in inbred lines MKP 60, MKP 61, MKP 63 and MKP 64, included as female parents in 8 hybrids registered in Belarus, Moldova and Romania. These lines have been involved in crosses with late and related early components in the initial material. The new inbred lines from the second cycle of selection inherited earliness, stalk and root lodging resistance, plant diseases tolerance, stay-green, other favorable traits from the original versions and have an average or a superior general combining ability. Some of them are used as parents in advanced and precommercial hybrids. Now in backcrosses, with 25% of genome, distinct and competitive private company hybrids from late group of maturity are used. The germplasm of Reid Iodent group, selected to higher plant density, is adapted to local stress abiotic factors, have superior grain yield, faster rate of ear dry down, saleable seed sizes and preferable as female parents in hybrids. In planned crosses of the breeding start material from BSSS-B37 group two inbred lines, considered to be the best for general combining ability, frequently are used. This alternative heterotic group in our germplasm collection is presented by a restricted number of early related inbred lines and a greater gain of favorable alleles is expected from late donors. Inbred lines from BSSS-B37 heterotic group are more affected by heat and drought and they can be used preponderantly as male parents. The most often used sources of initial material for improvement are backcrosses with analogues MKP 70MRf and MKP 71MRf as recurrent parents. To increase the diversity of genotypes it is used an alternate, modified backcrossing where recurrent parents are new experimental related inbred lines. Our preliminary results confirmed that introgression of a small amount (25%) of donor`s genome in BC1 populations can have significant effects on agronomic traits performance. In new breeding start sources for improvement of inbred lines from European Flint heterotic group, adapted to cooler temperatures and shorter seasons with longer days, commercial inbred lines MKP 22MRf and AN 615/95MRf are used. Late lines from BSSS-B37 and Lancaster heterotic groups that differ in flowering time by 10-15 days are involved as donors of higher combining ability. Before backcrossing to early recurrent parent, we select the best S3-S4 progenies that are phenotypically similar to the late inbred lines and possess the flint consistence of kernels. We concluded that the breeding program, where the start selection cycle of improvement is based on the best parents (inbred lines) of commercial hybrids, permits to develop new related lines directly included in performant heterotic patterns.