The success of a software development project depends on that the retrieved product complies with the user's specifications and to be completed within the time and within the budget established. Many software projects show the problem about that they are not being developed within the time set due to a bad assessment of the effort or duration of the software project. This research has the objective of determining the factors that affect the accuracy of the effort estimation in software projects using the Use Case Points as estimation method. A total of 37 primarily studies were selected. The results show that the environmental factors, the use cases complexity, the lack of use case standardization, technical factors and counting transactions are some of the factors that affect the accuracy of the Use Case Points method.