Objectives “Temporary Authorization for Use” (ATU) is a French compassionate program allowing the use of drugs before their marketing authorization (MA). Only hospital pharmacies are allowed to deliver these drugs, even for outpatients. After the MA, the reimbursement is maintained during the HTA assessment and national agreements on reimbursement and price. This period, so-called “post-ATU” and that has been reframed in 2014, should not excess 180 days as it sustains a “free pricing window” for pharmaceutical companies. The aim of this study is to assess the economic impact of the post-ATU period from the hospital perspective and to identify the determinants of its duration. Methods We included all drugs that have been through the post-ATU process since 2014. We censured data in May 2017. The financial impact was calculated for the 37 public hospitals of Paris (AP-HP), the largest university hospital in France. We conducted univariate analyses between potential explicative variables and wait time to obtain price and reimbursement. Drugs prices were based on APHP’s acquisition prices. Results