Internal audit quality plays key role in enhancing organizational performance in particular and safeguarding public resources in general. Therefore, the objective of this study was to examine the impact of internal audit quality on organizational performance of public sector selected bureaus in SNNPRS, Ethiopia. To this end, the researchers employed quantitative research approach with Explanatory research design where the effect caused by the independent variable on the dependent variable is observed through regression analysis. The primary data were collected using structured questionnaire from 112 respondents out of total 120 respondents’ selected using simple random sampling technique from purposively selected 15 bureaus in SNNPRS, which make the response rate of 93.33 percent. Then, both descriptive and inferential statistics analysis has been done through E-views version 9 in order to get the research findings. The research employed multiple linear regression models to investigate the effect of explanatory variables on the dependent variable (organizational performance) of bureaus in SNNPRS. Consequently, the result of regression analysis showed that, out of eight variables incorporated in the model, four variables such as independency of internal audit (positive), competency of internal audit staff (positive), management support (positive), and formal mandate of internal audit (positive) and statistically significant respectively. Whereas, other explanatory variables like objectivity of internal audit staff (negative), internal audit standards (negative), competent leadership (positive) and unrestricted access to audit evidence (negative) were not statistically significant respectively.