Sewage sludge is the solid, semisolid or liquid residue generated during treatment of domestic sewage. The occurrence of refinery sludge in considerably toxic amounts was reported by early workers in various aquatic ecosystems. It can act as an endocrine disruptor, interfering with biological functions such as reproduction, growth, development and the ability to cope up with stress. The present study investigates the endocrine activities of sludge using in vivo bioassays and the reproductive health of treated mice. For our study, a total number of six female albino mice with body weight ranging from 15 to 20g were selected and randomly divided into two groups. Animals of treated group identically received 50mg/kg body wt. sludge for 21 days. The treated sludge leachate from Numaligarh refinery could produce adverse effects at the tested dose. The examination of the treated female albino mice shows that oocyte nuclei degenerated, number of primary follicles were found less and the epithelial layer ruptured.Presences of atretic and degenerated corpus luteum were also noticed. In the present study, observed histological alterations in the ovary clearly establish that Bio-sludge possesses adverse physiological effects.The finding of the present study confirms that it is having a strong impact on reproductive system and its physiological function.