The clinical indications for anaesthetic drugs are developed through peer-reviewed publication of clinical trials. We performed a bibliometric analysis of all human research papers reported in nine general anaesthesia journals over 6 years (n = 6489), to determine any effects of the 2004 European Clinical Trials Directive on reported drug research in anaesthesia originating from Europe and the United Kingdom. We found 89% studies involved patients and 11% volunteers. Of 3234 (50%) drug studies, 96% were phase IV (post-marketing) trials. Worldwide, the number of research papers fell by 3.6% (p < 0.004) in the 3 years following introduction of the European Clinical Trials Directive (5% Europe, 18% United Kingdom), and drug research papers fell by 12% (p < 0.001; 15% Europe, 29% United Kingdom). The introduction of the Clinical Trials Directive has therefore coincided with a decline in European drug research, particularly that originating from the United Kingdom. We suggest a number of measures researchers could take in response, and we propose a simplification of the application process for phase IV clinical trials, emphasising patient risk assessment.