This paper presents the results of a reduced-scale physical model investigation into the behavior of retaining walls subject to cycles of wetting and drying due to rainfall infiltration. Reduced-scale model walls equipped with a water spraying system that can simulate the wetting process were first constructed and a series of tests were conducted with due consideration of different rainfall intensities and backfill soil types. The results indicate that cycles of wetting and drying process have adverse effects on the wall behavior, increasing wall deformation as well as earth pressure acting on the wall, and that the first cycle of wetting and drying process has more pronounced effect on the wall performance than the ensuing cycles. It is also shown that the degree to which the wetting and drying cycles affect the wall behavior depends greatly on the backfill soil type, and that the larger the fine contents, the greater is the effect of cycles of wetting and drying on the wall behavior. Practical implications of the findings from this study are discussed in great detail.