We have conducted a broad confidential inquiry among 401 hospital departments trying to estimate the number of patients affected with severe forms of hemoglobinopathies living in The Netherlands. With less than 30% response we have registered 559 patients in all age categories of whom 77.0% are affected with sickle cell disease and 17.5% with beta-thalassemia (thal) major. We estimate that the real figure could be around 800 patients, a figure more than six times higher than the number published in 1995 on which the reluctance to offer prevention was based. The actual figures and the incidence estimation of approximately 60 patients a year underline the urgent need for the official implementation of a prevention strategy in The Netherlands. During the last 5 years we have been working towards the implementation of a multi-intervention strategy for primary prevention using the existing structures of public health. The obstacles we have encountered to endorse such a strategy are discussed as a possible guide for other immigration countries.