This study was carried out on a commercial flock of Neimi sheep belonging to Al-Gassim Agric. Company in the mid-region of Saudi Arabia. The work aimed at studying the reproductive performance of this flock under accelerated lambing system. The traits used to  determine reproductive efficiency were fertility traits (i.e. conception rate, ewes lambed/ ewes joined, ewes aborted/ewes conceived and ewes with stillborn lambs/ewes conceived), fecundity traits ( lambs born and weaned/ewes joined) and prolificacy traits (litter size at birth and weaning). Age of ewe affected significantly ewes lambed/ewes joined, ewes aborted/ewes conceived and lambs born and weaned/ewes joined. Generally, all traits increased with age except percentages of ewes aborted and those with stillborn lambs which decreased with age but increased again for the eldest ewes. Autumn-bred ewes had the best reproductive performance, whereas those bred in winter had the worst. The effect of breeding season was significant on all traits except on litter size at birth and weaning.