In spite op compulsory voting, the number of non-voters increased at the last general elections in Belgium to 7.3 per cent. This evolution can largely be explained by demographic factors. The number of blank or invalid voters reaches nearly the same level. Concerning this form of political non-participation, we noticed considerable differences occur between the types of elections (local, provincial, House, Senate, European) due to factors such as the importance and the proximity of the proper institution, the social distance between candidate and citizen and the main issue of the elections. The analysis of both phenomena over time at the level of the individual voters based on surveys shows that electoral absenteeism is rather accidental, white blanc and invalid voting is more permanent. From the analysis of absenteeism and blanc and invalid voting emerge on the one hand socio-economic factors (like age, gender, professional activity, income, marital status and family composition) which jeopardize electoral participation in a direct or indirect way, and on the other hand, attitudes and behaviour reflecting political indifference, alienation and hostility (like low levels of political interest, information, knowledge, satisfaction, party identification, and participation).