Abstract: The rainfall interception loss in a tropical forest was investigated in this study. The 9 month data was collected with 78 rainfall events, 73 events with throughfall and 72 events produced stemflow. Two study plots were selected at Bukit Lagong Forest Reserve, Kepong, Selangor. The measured interception losses are compared with the calculated intercepted losses compute by using original Gash Model. The study show that the measured interception loss for Plot 11 and 12 is 305.8 mm and 269.11 and the calculated interception loss is 364.27 and 318.8 mm, respectively.