The objective of this study was to examine structural, histological and biochemical properties of overripped oocytes of the Persian sturgeon (Acipenser persicus). Oocytes (ripe or overripe) were removed from wild pre-spawn Persian sturgeon during spawning season run to the river of the southern Caspian Sea. Overripening in Persian sturgeon oocyte had a negative effect on egg viability. Thepercentage of eggs fertilized and hatching rates in overripe oocytes indicated a significant decline compared with the ripe oocyte (P<0.05). In the ripped oocytes from Persian Sturgeon broodstocks, four layers of zona radiata were clearly separated and the yolk was made up of homogenous particles and its perivitelline space shape had no considerable difference in different regions. Where as in overripped oocytes, zona radiata layers vanished and became an integrated layer, while the yolk distribution turned into heterogeneous and was more accumulated in the animal pole. The perivitelline space shape varied among different areas of overripped oocyt. The most notable difference were observed in the oocyte fatty acid profiles, which can be showed the higher concentration (P<0.05) of saturated fatty acid (SFA) in ripe oocytes (26.29±1.76) than overripe oocytes (21.70±1.53). Moreover, difference in ω-6 fatty acids were higher (P<0.05) in overripe oocytes (6.21±0.33) than ripe oocytes (4.42±0.37). SFA was dominated by palmitic acid, whereas MUFA was dominated by oleic acid in oocytes. The results obtained in this experiment specifies that, in addition to the differences in the zona radiata and oocyte follicular layers, some fatty acids in the Persian sturgeon oocyte such as palmitic acid, palmitoleic acid, arachidonic acid and eicosapentaenoic acid can be used as key factors for the diagnosis of overripped oocytes.