Dissertation (Msc Accounting and Finance)The study assessed the factors affecting the effectiveness of internal audit function in Tanzania Local Government Authorities. Specific objectives were to assess the influence of quality assurance review on the effectiveness of internal audit function, to assess the influence of information technology on the effectiveness of internal audit function and to examine the influence of internal audit charter on Local Government Authorities. The study used cross-sectional and correlational designs. Collection of data was done via email by sending 370 questionnaires to internal audit managers and internal audit officers of 185 LGAs of which 210 respondents responded to the questionnaire. Analysis of data was done by using descriptive statistics and multiple linear regressions. The study revealed that quality assurance review is effectively performed in Tanzania Local Government Authorities. Additionally, it was revealed that internal auditors are not fully equipped in the use of information technology in Tanzania Local Government Authorities. Moreover, the study revealed that internal audit charter is adhered to in Tanzania Local Government authorities. It is recommended that Tanzania’s LGAs should improve the quality assurance review, the information system used and the internal audit charter since these variables have a good impact towards the effectiveness of the internal audit function.