The purpose of this study in to investigate factors that are related to teachers' attitudes and perception of self-efficacy towards pupils with disabilities and the problems teachers experienced in the implementation of inclusive primary education in Tanzania. The study involved a sample of 100 teachers from 10 inclusive schools in Dar es Salaam. The instrument included questions/items regarding (a) background information of teacher and school characteristics and about the type of disabilities of the pupils that are included in the teacher's classroom, (b) teachers' attitudes and self-efficacy regarding pupils with disabilities in inclusive education (Likert scales) and (c) statements to measure the problems that teachers face in the implementation of inclusive education. First, the findings show that demographics like gender, class size, type of disability and training in special needs education did not relate significantly to teachers' attitudes and self-efficacy towards inclusive education. Furthermore, the results revealed that teachers face a lot of problems in the implementation of inclusive education, specifically in managing pupils with different disabilities, shortage of teaching and learning materials, lack of training and poor working environments. Multiple regression analysis showed that (a) working experience in inclusive education is significantly and positively related to attitudes towards including pupils with disabilities in mainstream education and (b) teachers with low self-efficacy face more problems with the implementation of inclusive education.