The Hydrological Simulation Program – FORTRAN (HSPF) in interface with the Better Assessment Science Integrating Point and Nonpoint (BASINS) was used to evaluate the impact on hydrology components of the Luxapallila Creek watershed due to different land use/land cover (LU/LC) databases. The 1,770-km2 watershed is located in Alabama and Mississippi. Simulation of the watershed processes were tested at the hillslope and at the watershed outlet for the period between 1985 and 2003. Three LU/LC databases were evaluated: the GIRAS, the Moderate Resolution Imaging Spectroradiometer (MODIS), and the National Land Cover Data (NLCD). The three LU/LC databases showed that more than 70% of the watershed area is covered by forest. Forest areas produced small changes among databases. Forest cover mechanisms were the main source of water losses. The model was more sensitive to daily time steps than annual periods when the MODIS and NLCD datasets were compared to the GIRAS database. In general, the MODIS dataset showed a higher variation on hydrology simulations than the NLCD database when both LU/LC databases were compared to the GIRAS database.