Grain refinement of Al-Si alloys has been a long subject of study with various theories still being discussed. The efficiency of grain refiners, fading effect, poisoning effect, and selection of the optimum ratios of particularly Ti/ B ratio has been the focus of many researchers. In this work, different grain refiners were added to Al11Si alloy and statistical analysis of tensile properties was conducted by means of Weibull analysis and survivability plots. It was aimed to compare the reproducibility and reliability of mechanical properties of different grain refiners. Ti free B, Nb, and chemically introduced MTS were investigated. It was found that the DAS and SDAS were not dramatically changed but the reliability of the tensile properties was significantly varied. 0.03 wt% Nb added alloy revealed the lowest reproducibility with lowest tensile values whereas 0.1 wt % Nb and MTS exhibited the most reliable and highest tensile properties.