Background: Chemical castration is one of the methods of non surgical contraception which has been suggested as a fast and low cost alternative to control a wide range of canine population.Methods: The potency of intra-testicular 20% calcium chloride solution was tested in 12 fertile, healthy and stray adult male dogs. Dogs were divided randomly into two groups, consisting six animals in each. The animals of group-I were administered intra-testicular 1.0 ml of 20% calcium chloride solution. Bilateral intra-testicular injection was performed using 21 gauge needle directed from the caudo-ventral aspect of each testis approximately 1 cm from the cauda epididymis and towards the dorso-cranial aspect of testis as per the procedure adopted by Jana and Samanta (2007). In group-II, 1.0 ml of normal saline was injected intra-testicular as placebo. Its efficacy was assessed by testicular morphometry, scrotal circumference (on day 0, 7, 15 and 30), histo-morphology (on day 0 and 30) and serum testosterone assay (on day 0, 15 and 30 of treatment).Result: The testicular morphometry of both the testicles was found to be increased size of testes significantly on day 7 in the treatment group as compared to day 0 and then decreased gradually and significantly on day 15 and 30. Histo-morphological study revealed significant changes including complete derangement of seminiferous tubules on day 30 post-treatment. Out of six animals the testes of four animals represented complete destruction of outline of seminiferous tubules. The germinal epithelium and Leydig cells were degenerated and parenchyma was replaced by fibro-collagenous tissue which was evident by the presence of numerous fibrocytes and fibroblast. There was no evidence of mature germ cells in section of both the testes. In some areas small blood capillaries were observed which may indicate neo-vascularisation. Discrete inflammatory infiltration of leucocytes was also observed in the parenchyma. Decrease in serum testosterone level after the end of study, i.e., day 30 indicated degeneration of Leydig cells. It can be concluded that 20% calcium chloride solution has a potential for testicular degeneration and thus sterilization of male dogs.