Abstract: This study was conducted to determine the water quality of the Relau River which is situated within the National Forest Reserve at Merapoh, Pahang. The study was conducted at three stations and water sampling was conducted three times i.e., in October, November and December 2011. The parameters analysed were the temperature, turbidity, Total Suspended Solid (TSS), pH, Dissolved Oxygen (DO), Biochemical Oxygen Demand (BOD), total coliforms and faecal coliforms. In addition to total and faecal coliform, the presence of Leptospira as an additional biological parameter was included due to an increase in the incidence of Leptospira presence in water bodies reported over the recent years. According to the Interim Water Quality Standards for Malaysia (INWQS), the values for all parameters in Relau River, except for the BOD were classified between Class I and Class II. Based on BOD values, the river was categorised as a Class III. The one way Analysis of Variance (ANOVA) with confidence level of 95% shows that all water quality parameters measured exhibited no significant differences between the three sampling stations.