Abstract: Background and Objective: Mud crab, Scylla tranquebarica has been reported to be present in Sabah coastal waters and this specie is one of commercially important crustaceans in the trade markets as demand that has been reported to be increased every year. However, high demands had caused exploitation to this species in Asia and there is still lack of in-depth study about this species mainly on sperm quantity and sexual maturity size. The present study was carried out to investigate the sperm quantity and sex maturation stages based on histology examination. Materials and Methods: Twenty of S. tranquebarica’s male were dissected and the testes were dissected out and divided into two parts where ¾ was used for determination of sperm quantity and ¼ was used for histological examination. The sperm were observed by using microscope under 40x magnification and the quantity were count by using haemacytometer. For histological observation, the testes were fixed in Bouin’s solution for less than 24 h, dehydrated pass through a series of increasing ethanol concentration, cleared with xylene, immersed in paraffin and formed a tissue block. The samples were stained by pass through a series of xylene, decreasing ethanol concentration, hematoxylin and Eosin Y. Results: There was a significant difference between Body Weight (BW), Carapace Width (CW) and sperm quantity with range of body weight for male S. tranquebarica. The highest sperm quantity was recorded on S. tranquebarica with the body weight; (401-500 g). Conclusion: The study concluded that the maturity size of S. tranquebarica was at 246.04 g in BW and 10.6 cm in CW.