At present, a number of newly satellite-derived precipitation estimates are freely available for exploration and could benefit the hydrological community. This study aimed to evaluate the Tropical Rainfall Measuring Mission TRMM 3B42 rainfall estimate algorithm in forest basins in Northern Tunisia. We selected 77 events, with 50 mm/day heavy rainfall as selection criteria, for at least one station of the study area observed during 2007, 2008 and 2009. Rainfall stations were interpolated using the inverse distance method. Results were discussed in terms of the TRMM product accuracy in comparison with rain gauges over the forestry zone (169 stations). The Pearson’s correlation coefficient between satellite estimations and ground maps reached 0.7 for some events and were weak for others. The comparison results of TRMM algorithm over forestry zone within Northern Tunisia shows a weak difference in terms of false alarm ratio (FAR), and bias. However, it shows a better detection for the whole of Northern Tunisia in terms of correlation coefficient and the probability of detection (POD). Some uncertainties have been found, across the TRMM algorithm over forestry region. Thus, the evaluation of satellite algorithms before use as input for other models is recommended.