Background: All the cells in human body need water to carry out their function properly. Water or any fluid consumed by an individual is one of the key factors that determines the hydration status. Whenever the ambient temperature is more than the body temperature, water promotes the release of heat from the body. The construction workers are exposed to direct sunlight and are more prone for heat related illness (Occupational Heat Stress). During prolonged work periods in the heat, the high sweat rates leads to progressive dehydration. Aim:: To assess the hydration status among construction workers using sweat rate. Materials and Methods: This study was carried out during winter (month of December) and involved 50 male construction workers aged 30-60 years, from a construction site in Chengalpet, Tamil Nadu, South India. This study included environmental heat assessment using Wet Bulb Globe Thermometer (WBGT) monitor. Sweat rate was calculated using the Canadian sports association method. Results: This study revealed that 52% of the construction workers studied had a high sweat rate, 18% of the workers had a moderate sweat rate and 30% of workers had a low sweat rate. Conclusion: The calculated sweat rate was high in more than 50 % of the construction workers in our study, which if continued to progress could have lead to dehydration and other serious health disorders like renal failure. A proper plan should be made to minimize the sweat rate by taking rest in between the work and by providing fluids during work.