Two companion post-marketing studies have evaluated the frequency of adverse events amongst patients receiving atracurium. In this second report, we describe the Scottish study and discuss findings in both centres. In this study we compare the frequency of adverse events in 477 patients receiving atracurium with those in 484 patients who received vecuronium. The frequency of reported serious adverse events was low during surgery and in the recovery room. Although the overall incidence of adverse experiences was slightly lower after atracurium, there were no significant difference between the groups in frequency of major adverse events. This type of study is believed to be of value in the future surveillance of new drugs for hospital use.