Background: Infertility is one of the commonest gynaecological problems encountered in practice. In many of the couples who deserve treatment, the conventional methods of treatment do not meet their needs. IVF-ET has become the mainstay of treatment for managing such patients. Several factors have been mentioned to affect the outcome. Bacterial contamination of the embryo transfer catheter is one such factor although the result of findings in this area is inconclusive. The cost of IVF-ET treatment is high and result relatively poor. It is therefore important to research into factors which can affect outcome in other to improve the result of treatment. Objectives: To assess the effect of bacterial colonisation of the embryo transfer catheter tip on the clinical pregnancy rate in an IVF-ET treatment. Methods: This is an analytical cross sectional study among women undergoing IVF-ET treatment at the University of Benin Teaching hospital, HRRP unit. The patients who were recruited for IVF-ET treatment and who met the inclusion criteria had the tip of the embryo transfer catheter cultured. The patients were grouped into Positive (bacterial isolated) and Negative (no bacterial isolated) based on the culture result. The clinical pregnancy (primary outcome), implantation rate and multiple pregnancies between the two groups were compared.