Pest behaviour of long tailed macaque (Macaca fascicularis) have been researched in Sekolah Menengah Kebangsaan (SMK) Tinggi Port Dickson Negeri Sembilan, Peninsular Malaysia. The location of the study is concentrated in SMK Tinggi Port Dickson and observation of monkey pest behaviour was studied from 0800 and 1200 and 1500 and 1900 for six days a week for about 25 days. Intensive direct observation is done using the interval scan sampling method which is every 10 minutes. In addition, this study based on a questionnaire was conducted about knowledge, opinions, and human attitudes towards humans. Pest behaviour by monkeys the highest monitored was breaking into school area (37.17%), followed by messing up garbage cans (24.08%), damage facilities (16.75%), littering (16.49%), stealing (3.14%) and the lowest was disturbing people (2.36%).