According to the literature, MODIS burned area product MCD45 has been shown to have low reliability in the tropical Andes, with omission errors around 50%. Instead, Landsat images can provide good results but current processing methodologies are very time consuming. This study presents a new method for the tropical Andes, based on spectral unmixing applied to MODIS and Lansat images, with the aim of improving the methods currently available to estimate burned area in the region. Results show that the technique is not appropriate for MODIS images, which have not enough spatial resolution distinguishing between burned and unburned pixels. However, spectral unmixing applied to Landsat images lead to results with only 20% of omission errors and 9% of commission errors.