A research report submitted to Mzumbe University – Mbeya Campus College in partial fulfillment of the requirement for the award of degree of Bachelor of Accountancy and Finance (BAF-BS) of Mzumbe UniversityThe study was about assessment of the effectiveness of financial internal control in public institutions. Sub treasury in Mbeya being the case of the study. The unity of inquiry involved employees of sub treasury which included management, middle and lower cadre employees. The study sample size was 30 employees out of 40, employees who were obtained through simple random and sampling technique. The study sample frame was sub treasury’s employees register. Data collection involved questionnaires and observation. Questionnaires were distributed to employees selected as sample and observation were done to all employees. Data were processed and organized in table and graphs, thereafter analyzed using MS excel. Findings shows that, internal control has contribution toward permitting the appropriate record keeping and reporting of financial related matters, and it helps accountants to prepare financial reports. The study sought to ascertain whether the effectiveness of financial internal control is affected by factors like Management and organization structure, environment and co- workers. The study reveal that majority of respondents see management and organization structure is highly affect the effectiveness of financial internal control. Therefore to make internal control effective, management should support its conduct.