Abstract: Background and Objective: Leptin has beneficial effects on mammalian oocyte maturation, development and enhances the transcription levels of developmentally important genes. The aim of present study was to determine the factors affecting in vitro maturation of sheep oocytes. Materials and Methods: Ovaries from slaughtered sheep were collected from local Abattoir of Hyderabad (India). Four experiments were conducted. Experiment I: Efficacy of oocyte retrieval methods in relation to oocyte quality and quantity were studied. Experiment II: Effect of season on sheep oocytes quality and numbers were recorded. Experiment III: Determine the effect of presence of Corpus Luteum (CL) on oocyte yield. In experiment IV: Studied effect of leptin addition on maturation media to compare the IVM (In vitro maturation) status like cumulus-oocyte complexes expansion and M-II stage of sheep oocytes in combination with traditional in vitro maturation medium. Oocytes were cultured with different concentration of leptin. T1: 10, T2: 20, T3: 50, T4: 100 ng mL–1 and T5: Control incubated at 39°C in 5% CO2 under humidified atmosphere for 24 h. Results: Total 3241 oocytes were retrieved from 1520 sheep ovaries. The percentage of good quality oocytes was higher in the aspiration method (65.8%) as compared to the slicing (54.2%) and post aspiration slicing method (36.1%). The oocytes recovery recorded during spring (March-April) was significantly higher as compared to winter and summer. On an average 1.88±0.14 oocytes per ovary were recovered from ovaries without CL as compared to ovaries with CL 1.37±0.1. The leptin 20 ng mL–1 shows Cumulus-Oocyte Complexes (COC) expansion (76.80±1.59) and polar body extrusion (50.63±3.94) whereas, leptin-20 ng mL–1 with IVM medium also exhibited Cumulus-Oocyte Complexes (COC) expansion (81.90±1.87) and polar body extrusion (56.87±2.92). Leptin 20 ng mL–1 with IVM medium shows best result on in vitro maturation of sheep oocytes. Conclusion: This study findings suggested that aspiration method was best for oocyte retrieval. Quality and numbers was better on spring (March-April) season as compare to winter and summer. The oocyte yield was significantly lower on ovary with CL. Supplementation of leptin 20 ng mL–1 with IVM shows best result on in vitro maturation of sheep oocytes as compare leptin alone and control.