Objectives:To provide an update to the 1999 French guidelines on " Muscle relaxants and reversal in anaesthesia" , a consensus committee of sixteen experts was convened.A formal policy of declaration and monitoring of conflicts of interest (COI) was developed at the outset of the process and enforced throughout.The entire guidelines process was conducted independently of any industrial funding (i.e.pharmaceutical, medical devices). The authors were required to follow the rules of the Grading of Recommendations, Assessment, Development and Evaluation (GRADE ?) system to assess the quality of the evidence on which the recommendations were based.The potential drawbacks of making strong recommendations based on low-quality evidence were stressed.Few of the recommendations remained ungraded. Methods:The panel focused on eight questions: (1) In the absence of difficult mask ventilation criteria, is it necessary to check the possibility of ventilation via a facemask before muscle relaxant injection? Is it necessary to use muscle relaxants to facilitate facemask ventilation? (2) Is the use of muscle relaxants necessary to facilitate tracheal intubation? (3) Is the use of muscle relaxants necessary to facilitate the insertion of a supraglottic device and management of related complications? (4) Is it necessary to monitor neuromuscular blockade for airway management? (5) Is the use of muscle relaxants necessary to facilitate interventional procedures, and if so, which procedures? (6) Is intraoperative monitoring of neuromuscular blockade necessary? (7) What are the strategies for preventing and treating residual neuromuscular blockade? (8) What are the indications and precautions for use of both muscle relaxants and reversal agents in special populations (e.g.electroconvulsive therapy, obese patients, children, neuromuscular diseases, renal/hepatic failure, elderly patients)? All questions were formulated using the Population, Intervention, Comparison and Outcome (PICO) model for clinical questions and evidence profiles were generated.The results of the literature analysis and the recommendations were then assessed using the GRADE ? system. Results:The summaries prepared by the SFAR Guideline panel resulted in thirty-one recommendations on muscle relaxants and reversal agents in anaesthesia.Of these recommendations, eleven have a high level of evidence (GRADE 1±) while twenty have a low level of evidence (GRADE 2±). No recommendations could be provided using the GRADE ? system for five of the questions, and for two of these questions expert opinions were given.After two rounds of discussion and an amendment, a strong agreement was reached for all the recommendations. Conclusion:Substantial agreement exists among experts regarding many strong recommendations for the improvement of practice concerning the use of muscle relaxants and reversal agents during anaesthesia.In particular, the French Society of Anaesthesia and Intensive Care (SFAR) recommends the use of a device to monitor neuromuscular blockade throughout anaesthesia.