Optical sensors have limited application in tropical humid forest regions because of the constant cloud cover, nadir viewing and shallow forest penetration capability. Orbital radar systems, however, are specially suited for studies in those regions because they are quite independent on the weather conditions and illumination; besides that, the side looking view increases their sensitivity to topography and surface roughness. In this paper the synergism between RADARSAT and TM LANDSAT data is explored for the enhancement of relief information. The study area is located in the State of Rondonia, Brazilian Amazon. This area was selected due to the flat terrain where the use of RADAR data is essential to the enhancement of the topographic texture and micro and macro surface topography. Optical and radar data fusion was performed by IHS transformation. The resulting product was submitted to photo-interpretation. The radar component of the integrated data was useful to map hills and crests in the region of large geological control. The drainage pattern showed organized and disorganized multidirectional shapes and unidirectional shapes. The micro topography and the low incidence angle provide by the S2 view responded for the modulation of the radar backscatter. TM contribution was related to the spectral differences between geomorphological units. The integration of optical and SAR data was essential to the extraction of relief information from the flat topography of the Amazon region.