 The study evaluates the impact of five different rainfall products on streamflow simulation using HEC-HMS in the upper catchment of triane reservoir in Vietnam. Results show that TIMM and GPCC data provide the best match to rain gauges data, indicating they could be alternative solutions for hydrological modelling in developing countries where networks of rain gauges are sparse. This article was authored by Pham Phai Tau NHI, Dao Nuyen Khoi and Nuyen Xien Hoan.