In this Germany-wide, multi-center, epidemiologic study we would like to evaluate if the use of muscle relaxants, or signs of their prolonged effect beyond the end of the operation/anesthesia (PORC), affect the further in-hospital stay and post-operative morbidity and mortality. The sampling in 8 German hospitals should determine the number of patients with clinically relevant signs of muscle weakness at the time of arrival in the post-anesthesia care unit. Therefore a data entry form has been developed by the principal and sub-investigators of the 8 participating study hospitals. This data entry form enables the staff in charge of the post-anesthesia care unit to acquire and to document residual neuromuscular blockades. The sampling will be done in the 8 participating hospitals on 21 randomized working days over a period of 24 hours. To identify the potential risk factors for postoperative residual curarization, the known predictors for neuromuscular rest blockades are recorded as well. Known predictors are for example: type and amount of muscle relaxant, duration of operation and anesthesia, surgical procedure, patients' age, anesthesia-technique, antagonization of muscle relaxant or neuromuscular monitoring. Further, the patients' progress in the post-anesthesia care unit is documented.