Classification of JERS-1 (Fuyo-1) SAR data from the northwestern portion of Brazil was performed using the semivariogram textural classifier (STC). This is a deterministic, supervised classifier which provides the option of combining textural and radiometric information. Textural information is expressed by the semivariogram function; radiometric information is conveyed by the mean digital number (DN) value. Results have shown that STC allows vegetation units and water bodies to be discriminated and tentatively mapped, suggesting that this is a promising approach for environmental monitoring of rainforest regions using SAR data.