Abstract: The objective of this paper was to establish a level A in vitro-in vivo correlation (IVIVC) for goserelin acetate extended release microspheres for injection. Three kinds of goserelin acetate microspheres with different release rates were prepared and the critical physicochemical properties, such as drug loading, particle size, glass transition temperature and morphology were characterized. In vitro dissolution test of the prepared goserelin acetate microspheres was performed using sample-and-separate method at 45℃ in 5% (v/v) methanol. The morphology of the microspheres and the molecular weight of poly (lactic-co-glycolic acid) (PLGA) of the prepared goserelin acetate microspheres were investigated to research the release mechanism of microspheres. The plasma concentration of goserelin was detected after intramuscular injection of goserelin acetate microspheres to SD rats, and correlated with the in vitro release profiles after processing by percent AUC method. The pharmacokinetic experimental protocol of goserelin acetate microspheres for injection in SD rats was approved by the Animal Ethics Committee of Shandong Luye Pharmaceutical Co., Ltd. The results indicated that the developed sample and separate method was able to detect differences in the release characteristics of the prepared goserelin acetate microspheres, and the in vitro-in vivo correlation of goserelin acetate microspheres was excellent (r > 0.98) and had good predictive ability in SD rats.