ABSTRACT The present work carried out to study the effect of four introduction cycles ( February, March, April, May) of F1 Carniolan and F1 Italian virigin queens introduced on 3- and 5- comb mating nuclei of the same and inverse subspecies ( genotype) on virigin acceptance and mating success. The experiments were made in a private apiary located at Zagazig District, Sharkia Governorate, Egypt during 2016 and 2017 seasons. Results revealed that virigin acceptance rates for both F1 Carniolan and F1 Italian virigins were relatively higher in February and March introduction cycles, recording between 90.0 – 100.0% acceptances in the two seasons. The least acceptance rates were exhibited in April introduction cycle for both hybrids, meanwhile the least meating cuccess was recorded for May cycle in the two seasons. The rate of acceptance was relatively similar in both 3- and 5- comb matching nuclei. Meanwhile, meating cuccess of virigins of both subspecies was relatively higher in the stronger mating nuclei (5- comb nuclei). Introducing virigin queens in mating nuclei of the inverse genotype, showed varied acceptance and mating success values between the two virigin genotypes, where F1 Carniolan virigin queens introduced on and 5- comb F1 Italian matcing nuclei showed means of 77.5 and 80.0% acceptances, meanwhile F1 Italian virigin introduced on and 5- comb F1 Carniolan matcing nuclei showed means of 82.5 and 85.0% acceptances when introduced on Carniolan matcing nuclei in the two seasons, respectively. In addition, mean matcing success rate was relatively higher for F1 Italian queens introduced on 5- comb F1 Carniolan mating nuclei that recorded 96.88 and 94.10% compared to 85.07 and 84.28% for F1 Carniolan queens mated in F1 Italian nuclei in both seasons, respectively. Key words: Apis mellifera L., mating success, F1 Italian hybrid, F1 Carniolan hybrid, queen acceptance, nectar flow, aggressiviness.