A study on rapid routine HIV screening was mainly performed by nurses in 29 Emergency departments (EDs) of Paris urban area. Individual and collective covariates of healthcare staff participation were analyzed, along with positioning regarding the nurse autonomy for this activity. International studies confirm the interest of nurse screening. 25 interviews with nurses, nurse supervisors and physicians were performed in 5 departments. The staff participation is associated with motivation for HIV or prevention, a multidisciplinary approach, a generalist background or short professional experience, as well as the perception of an easy process. Most of nurses succeeded in offering, realizing the test and disclosing the negative results to patients. This activity was considered as an autonomy vector. After training sessions, HIV screening could become part of the nurse mandate of prevention in collaboration with physicians. This collaboration addresses a classic work division for nurse supervisors and doctors. However, a systematic implementation of HIV screening in EDs seems not to be executable because of structural constraints. The autonomy for nurse-initiated HIV screening enlarged to prevention and public health activities is positively considered by nurses.