Background Health impact assessment (HIA) is a method aimed at anticipating the potential effects of proposals on health prior to their implementation in order to include health issues in decisions made outside the health sector. It is structured in several steps. The first one (screening), aimed to decide if a full assessment is required or not, is poorly documented. In France, the interest shown for HIA has led to a growing number of experiments, which questions the quality of practices linked to this step and its capacity to fulfil its purpose. This study describes how screening is implemented, explores the main issues at this stage, the decision-making process and to what extent it conditions the HIA's success. Methods All HIAs undertaken between 2011 and 2019 were listed in order to provide a picture of the process. Then, we focused on the 3 most involved regions to describe the screening process (reports, interviews, observation). Drawing on quality standards and literature review, we built an analytical framework to analyze practices, the interface with other approaches, the influence of the local context and the HIA's success factors. Results 59 HIAs were identified. Among them, 54 have gone beyond screening. HIAs are applied to land use planning (72%,) policies (19%), equipments (9%) and are carried out by public organisations (37%), private firms (35%), universities (15%), municipalities (13%). 11 regions (out of 18) conducted at least one HIA and practice varies significantly across regions. Case studies in 3 regions (36 HIAs) show that screening length and depth vary greatly. Its features depend on political commitment to HIA, advocacy for HIA, guidance, relationship with local authorities, technical skills. Overall, screening is more dedicated to promote HIA and select a pilot project than to study the HIA's relevance and feasibility. Conclusions Since screening is methodologically poorly underpinned, it weakens HIA's quality and efficiency whatever its duration.