Intelligent video analysis is a problem of great importance for applications such as surveillance and automatic annotation. We present, in this paper, a hybrid, knowledge – based approach for object recognition in video sequences. Objects are modelled, in the signal level, through the visual descriptors defined by MPEG-7, the ISO standard for description of audiovisual content and in the semantic level, through the semantic relations defined by MPEG-7. The method of video analysis is synopsised as follows: first, moving regions are extracted using an active contour technique. Second, visual descriptions of the moving regions are extracted and are matched with the ones defined for recognizable objects.