The aim of this study was to investigate the effect of the administration of half or full dose of prostaglandinF2α (PGF2α; Gestavet Prost, d-cloprostenol, HIPRA®) injection in a routine synchronization protocol following theend of the breeding period including intravaginal sponge (medroxyprogesterone acetate; Espanjovet, HIPRA®) andeCG (Oviser 500, HIPRA®) on certain fertility parameters in ewes.Two hundred thirty-eight Awassi yearlings (agedone year old) divided into two groups:116 ewes received a half dose (HSDP; 37.5 μg) of PGF2α and 122 ewes receivedfull dose (FSDP;75 μg).The pregnancy rates were 67.2% and 72.1% for HSDP and FSDP, respectively (P>0.05).The lambing rates were 64.7% and 63.9% for HSDP and FSDP, respectively (P>0.05).The single lambing rate inHSDP(94.7%) was higher (P<0.05) compared to that in FSDP (73.1%). The twin and multiple birth rates of FSDPwas higher (P<0.05) than HSDP. As a result, it was inferred that aHSDP could be used in Awassi yearlings withoutexperience of lamb care and in a herd in which single lambing was preferable. Moreover, due to the fact that it is moreaffordable and not detrimentalto fertility, it was concluded that HSDPcan offer an advantage in large flocks and can beused for manipulating fecundity ratesin yearlings.