Introduction Apricot production has many risks, mainly manifested during the postdormancy and fl owering periods.  To improve the yield stability it is fi rst necessary to develop (selection and implementation) new varieties (Pintea, 2002, 2003) with high adaptability to variable local micro climatic conditions.  Material and methods Biologic material is represented by 40 American introduced varieties and selections  being compared with main created in Rep. Moldova. There are employed methodical and methodological principles which are approved for breeding and genetics of fruit trees species ( Cociu V., Oprea Şt., 1989, Nicotra et all, 2006). Results and discussions Result of microscopic investigations of fl oral buds initiation and development of fl oral parts in the summer-autumn period there are no distinguished principled differences between American varieties and Moldavian ones. Practically within all varieties there are noticed the same morphogenetical  dynamic of initiation and development of whole perianth, commencement of formation of stamens and ovarian loge. American varieties and selections(mains – created for central California conditions) Lorna, Katy, Kettleman, Modesto, Helena, Nicole, Robada, P301-105, K-604-19, Wesley, K-611-150, Y103-253, Y604-75,  Rival  fi nished the profound biological rest already at December  20-25. In the same time another part of American varieties (for example: Stark Early Orange,  Cream ridge,  Henderson, Goldrich, Early blush, Tomcot, NJA-19, NJA-44 and others) continued to be in profound rest yet 4-5 weeks (until to second decade of January). During the same period get out of rest period the fl ower buds of autohtonous varieties.  After there main part of fl ower (being in buds yet) there are affected by frost of about 170C just in 4-6 days. Dynamic of fl oral development in buds of the majority of registered apricot varieties for our country there is comparatively more slowly. Beginning of fl owering of American genotypes, with earliest outgoing from biological rest of fl ower buds (during December) was earliest comparatively with  others Moldavian and American varieties (average terms –the third decade of Mars –second decade of April) maximum with 1- 2 days difference. In the conditions of Rep.Moldova American variety Cream ridge there is distinguished from the majority of studied varieties by more long periods of fl owering (1-2 days) and by delayed maturation of fruits (more than one weak). The both open fl owers and juvenile shoots of the American genotypes there are more susceptible  to moniliosis (Helena, Katy, Nicole, Wenatchee, Kettleman, Lorna, K-106-2, K 604-19, Robada and others). Conclusions 1. No signifi cant differences have been observed between American and Moldavian genotypes according to the time of initiation and differentiation of fl ower in fl ower buds.  2. The most of American varieties are more susceptible to the attack of Monillinia laxa than Moldavian ones. 3.The varieties Cream ridge, Stark Early Orange, Goldrich, NJA-42, Patterson there are interesting for utilization in intraspecifi c hybridizations because of the complex of valuable  features which are favorable manifested in the conditions of the republic of Moldova