This paper reports the results of the application of the conjoint measurement method (CM) to determine a monetary value of informal care. Compared to the normally recommended valuation methods, like the opportunity cost method and proxy good method, CM is probably better able to capture the heterogeneity of informal care. We developed a survey in which informal caregivers were asked to rate four different hypothetical informal caregiving situations, which differed with respect to care hours, care tasks and monetary compensation. Data were obtained from postal surveys. A total of 135 pairs of informal caregivers and care recipients with rheumatoid arthritis (RA) from the Netherlands returned a completed survey and were used in the analysis. Informal caregivers require an extra compensation of 1.00 euro per hour for providing one additional hour of the same informal care task (meaning that from the seventh to the eighth hour, they require 8 euro). For providing two extra hours of care, they require 2.00 euro compensation per hour. The relative valuation of informal care tasks is very diverse. Respondents require a compensation of 13.43 euro per hour for switching from providing light housework to personal care and 0.56 euro per hour for switching from providing personal care to heavy housework. Though CM is sometimes regarded as cognitively complex, 70% of the respondents were able and willing to evaluate the hypothetical caregiving scenarios. Elderly respondents especially had more difficulty with the method. In sum, CM is seen as a promising alternative for existing methods to determine a monetary value of informal care. The presented valuations of informal care can be incorporated in the numerator of a cost-effectiveness ratio in economic evaluations of health care.