Research has repeatedly shown that a large number of independently living oldest elderly are cared for by family members, friends or neighbours. This care is given either in combination with professional home care or without and it obviously reduces the financial burden for the state's health and social security system. Several authors suggest that, although very high levels of informal care are still present in Europe, this pattern will change in the near future. In view of monitoring the trends, we need sound and standardised procedures of measurement. The paper deals with the measurement of "informal care". By "informal care", we mean care provided by family members, friends and neighbours. Organised voluntary work is not included. The paper first describes sociological and socio-demographic research where informal care is a major theme. The study of (a) intergenerational relations, of (b) the relationship between formal and informal care, and of (c) social capital, including the analysis of living conditions of informal carers and the study of the combination of "care and career". We argue that there is a shift in measuring informal carers from the point of view of the care receiver towards the perspective of the care provider. However, looking at the procedures used in counting the proportion of informal carers from the carer's perspective in European research, a large variety is apparent. Any sound international comparison is therefore jeopardised. We describe the available methods in the second section. The paper proceeds with the presentation of a method developed in Belgium (Flemish region), in 2003. This method is based on the description of performed care tasks in the field of socio-emotional work, housekeeping and personal care. It allows the development of age and gender (and other) specific indicators. Furthermore it enables a risk-type analysis. The strengths and weaknesses of this approach are discussed. © La Documentation française. Tous droits réservés pour tous pays.