River water quality is important for ecological health. The Tembeling River is the main river flowing through the Pahang National Park and is used as a resource for navigation as well as for recreation purposes. Recreational use of water may offer health benefits to hu-man. Waters contaminated with chemicals that are either toxic or irritating to the skin or mucous membranes are unsuitable for recreational purposes. The objective of the study was to evaluate the heavy metal chemicals changes before and after monsoon. Water samples from five tributaries (Sg Tahan, Sg Keniam, Sg Trenggan, Sg Perkai and Sg Tenor) were monitored for temperature, pH, dissolved oxygen, and concentrations of eight dissolved metals (Ag, Cd, Cu, Cr, Fe, Ni, Pb and Zn) over six different sampling periods; 3 before the onset of the seasonal monsoon and three after the monsoon period. All sampling stations were located within the recreational zones, where conditions are ho-mogenous. Cr, Cu, Fe, Pb, Ni and Zn concentrations were significantly higher before the monsoon compared to the period after. However, concentrations of Ag and Cd showed an opposite pattern compared to the other metals. Seasonal patterns of Ag and Cd in the for-ested area were characterized by decreased concentrations of them following monsoon but gradual increased levels of Ag and Cd were recorded as the water flow reduced. Ag, Fe, Pb, and Cd were found to be present at higher concentrations than the recommended stan-dards. The sources contributing to high concentrations of metals were found to be of natu-ral origin. The results suggest that the water supply in the National Park is of acceptable quality for recreational purposes. However, continuous monitoring of environmental pol-lutants is essential in order to prevent any recreational water illness.