Industrial machinery fleets in Tanzania are critical for economic development but face significant operational challenges. A quasi-experimental design was employed to assess the performance of industrial machinery fleets in Tanzania. Data collection included surveys and monitoring logs. The analysis revealed that an optimised maintenance schedule reduced operational costs by 15% compared to baseline practices, with a standard error of ±3%. This efficiency improvement is particularly evident in equipment lifespan extension. The quasi-experimental design provided robust insights into the cost-effectiveness and operational efficiency of industrial machinery fleets in Tanzania. Adoption of optimised maintenance strategies should be encouraged to further enhance the performance and longevity of machinery systems. industrial machinery, fleet management, cost-effectiveness, quasi-experimental design, Tanzania The maintenance outcome was modelled as $Y_{it}=\beta_0+\beta_1X_{it}+u_i+\varepsilon_{it}$, with robustness checked using heteroskedasticity-consistent errors.