The reversibility of anoestrus caused by long-acting GnRH analogue (deslorelin), and the effectiveness of GnRH analogue to induce standing oestrous, and in consequence to the retardation of breeding season, was investigated. During the transition period, 26 fat tailed breed ewes were randomly divided into 3 groups. GnRH analogue Ovuplant and Suprelorin were inserted under the neck skin in group I (n=7) and group II, respectively. No administration was applied in group III (control group, n=10). Suprelorin was removed 60 d after the implant's insertion. The initiation of sexual activities based on the day of progesterone increase, and the first standing oestrous were 12.9±1.86, 34.7±9.69, 81.9±6.31, and 27.3±1.94, 48.3±9.24, 96.9±5.76 in control, Ovuplant and Suprelorin was administered to groups; respectively (P<0.001). In conclusion, deslorelin administration resulted in reversible anoestrus in ewes. During the 60 d experimental period, Suprelorin effectively suppressed sexual activity; therefore, Suprelorin could be used to delay the breeding season.