After a brief outline of the development of the medium radio in Belgium, and a concise summary of the radio supply in Flanders, we examine the topic of radio research. In Belgium, two studies, each employing a different method, measure listening behaviour and come up with sometimes conflicting results. The BRTN and the VAR have opted for a study based on diary notation by a panel. In section 2 we examine the experiences and lessons of the past three years. Young people, on the one hand, and elderly people, on the other hand, are less inclined to take part in a panel. The self-employed and the lesser educated are also more difficult to attract. Once they have started participating in the panel, the panel members who have collaborated faithfully for three years are primarily men of 55 years and older, executives and white-collar workers. The listening diary indicates a greater degree of radio reach, but a shorter average duration of listening. The listening diary also picks up on 'abnormal' listening behaviour: the brief periods of listening to radio stations which are not a part of the usual daily listening pattern, and listening outside the home. On the basis of our findings, we conclude that the diary method reflects actual listening behaviour more closely and is therefore more suitable for the monitoring of listening behaviour. For the analysis of the total radio landscape, particularly the smaller stations, and for the formation of listening profiles, a face-to-face survey, carried out within the framework of a major sample, can be interesting.