In the context of the growing proportion of seniors in the western world population and the efforts provided in home care services, we have developed a computer vision system for monitoring medication intake. The system detects automatically medication intake using a single low-cost webcam. Person detection and tracking over the video sequence is done using color-based techniques while the recognition of the medication intake activity is performed using our main contribution, a three-level scenario model. Experimental results in controlled conditions are shown and we discuss improvements to our system.