The most importantaim of this study was to determine the factors that affect consumers trust in ecommerce inAddis Ababa.Quantitativeapproach and explanatory researchmethod were employed. Moreoverdescriptive and inferential method of analysis was used. The primary data was collected by using five point Likert-scales for which 367 questionnaires were filled properly out of 385 distributed questionnaires. Pearson correlation coefficient(r) was used to determine the relationship betweeneach independent and dependent variable of which Perceived website,Perceived Security, and Perceived service quality are substantial association with 0.687**, 0.544** and 0.522** Consumers trust respectively.Perceived sizeat correlation result of 0.477**are moderate association with Consumers trust. Perceived reputationhas less association with consumers trust 0.367**Pearson correlation coefficient(r) .Moreover, regression analysis was computed to confidently determine which factors matter most, which factors can be ignored, and how these factors influence each other. From the survey result, perceived website quality is found to be the primary factor that affects consumers trust (B=0.481, P=0.001). While perceivedsecurity (B=0.264, P=0.001), perceived size (B=0.165, P=0.001) and perceived service quality(B=0.108, P=0.014) has significant effect in descending order. But perceived reputation has not significant effect on consumers trust (B=0.005, P=0.835)