Objectives. To estimate the incidence of symptomatic acute hepatitis B and the completeness of mandatory reporting (MR) of acute hepatitis B in France in 2010. Methods. The LaboHep survey was conducted among a random sample of 1,412 laboratories. An acute case was defined by the absence of known chronic carriage and the first-time laboratory detection of: 1) anti-HBc immunoglobulin (Ig) M ("IgM definition") or 2) anti-HBc IgM, or, in the absence of anti-HBc IgM testing, HBs antigen and total anti-HBc antibodies in the context of a significant increase in ALT ("broad definition"). The incidence of acute hepatitis B was estimated after multiple imputation of missing data and weighting. The completeness of the DO was determined by the ratio of the number of cases reported by laboratory technicians (DO) in 2010 to the estimated number of "reportable cases" for 2010 via LaboHep. Results. The number of new cases of symptomatic acute hepatitis B is estimated, according to the "IgM" and "broad" definitions respectively, to be between 1,021 [95% CI:779–1,263] and 1,622 cases [95% CI: 1,186–2,059], corresponding to an incidence of between 1.6 [95% CI: 1.2–2.0] and 2.5 [95% CI: 1.8–3.2] per 100,000 inhabitants. The completeness of the surveillance system is estimated to be between 15% and 9%. Discussion. The LaboHep survey made it possible to estimate the incidence of symptomatic acute hepatitis B and the completeness of the surveillance system, thereby demonstrating its methodological value. Its continuation will allow for monitoring changes in incidence, thereby contributing to the evaluation of vaccination strategies, in addition to the surveillance system, which needs to be revitalized. (R.A.)