The reduction of post-harvest applied pesticides in potatoes during storage or processing was investigated. After application of DDVP, chloropropham, chlorpyrifos and pyrethrin, potatoes were stored for 13 weeks or processed to prepare French fries without peeling, and the levels of pesticides were determined after each step. DDVP, chloropropham, chlorpyrifos and pyrethrins from potatoes were detected at the levels of 0.03%, 37%, 46%, and 2-35%, respectively, after 13 weeks' storage at room temperature; and at 0.1%, 1.3%, 7.7% and 5.9-10.1% after processing to prepare French fries. However, more than 99% of pesticides was removed by peeling.