In the present investigation the characteristic fatigue life prediction of A 356.2 T6 aluminum alloy has been statistically analyzed by log normal distribution. Fatigue tests were conducted on aluminum alloy specimen on rotary bending fatigue testing machine at six different stress levels. A step wise procedure is outlined to determine the number of specimen required at predetermined stress amplitudes. Details of generation of S-N curve for A 356.2 T6 aluminum alloy using a regression analysis is delineated. ANOVA is performed in order to check the significance of regression equation. The adequate sample size required for evaluating the average fatigue life of A 356.2 T6 with an acceptable error at 50 % probability and 90 % confidence level using log normal distribution is established from this study. The experimental results are presented in the form of R-S-N curves, which are helpful for designers.