This study was carried out to aid an establishment of guideline for safe use of boscalid in squash (Cucurbita spp.). Boscalid was sprayed on squash according to safe use guideline. Samples were collected 2 hr after spray at 1, 3, 5, 7, and 10 days, and was analyzed by GLC/ECD. The limit of detection of boscalid was 0.02 mg/kg. The biological half life of boscalid was found to be 2.5-2.8 days. The residual amount of boscalid 10 days before harvest was 13.68 mg/kg. The residue levels in boscalid was lower than the established MRL.