The experiment was conducted to determine the causative factors of poor fertility, hatchability, and their rectification in RIR breeds of chicken in Ethiopia. For crossing chickens were randomly allotted as RIR(♀)xRIR(♂),RIR(♀)xWL(♂),WL(♀)xRIR(♂),and WL(♀)xWL(♂). Each group was inseminated with equal number of spermatozoa on weekly basis. Pure RIR showed lower fertility and crossing of RIR with WL does'nt improve fertility of RIR chickens.Pure RIR eggs has lower hatchability as compared to pure WL. Crossing of WL(♀)xRIR(♂) showed higher improvement in hatchability. The egg weight loss in pure RIR was higher than pure WL and crosses during 18 days of incubation. Spermatozoa of RIR in RIR oviduct poorly withstood the effect of semen ageing. The poor fertility in RIR chicken was found due to both sex effects but for lower hatchability female was responsible, and further more water loss during incubation, failure to cover yolk sac in abdominal cavity and faster ageing in female tract were the causative factors for poor hatchability, and a simple method to count spermatozoa under field condition was developed.