This study was conducted to investigate optimum processing procedure of fresh-cut button mushrooms. The experiments were done with different processing parameters including washing method, washing time, sanitation, and cutting time. Fresh mushrooms were washed by swirling water (SW), lift type-immersion washing (LIW), or combined LIW and water spray (LI+WS). Mushroom samples were washed by LIW for 0, 1, 3, and 5 minutes separately. Mushrooms were sanitized with 0, 50, or 100 ㎕L-1 chlorine solution (pH 7) for 60 seconds. Mushrooms were sliced at different times (before washing, after washing, or after drying). The combined washing treatment, LIW+WS was effective in maintaining better appearance and higher Lightness color value among treatments. Optimum washing time to remove foreign materials and maintain color was 3 minutes when mushrooms were washed by LIW. Samples sanitized with 50 ㎕L-1 chlorine reduced initial aerobic bacterial population and had only slight residual chlorine odor. Fresh-cut mushrooms sliced after washing had the lowest loss among samples. The optimized washing, sanitation, and cutting time parameters can be used for sequential processing of fresh-cut button mushrooms.