Abstract: Objective To discuss the reporting standards and quality of adverse events (AEs) in clinical researches. Methods The reporting standards of AEs on three occasions were analyzed and the quality requirements of the original data when coding with MedDRA terminology were illustrated. Results Aggravation of researched diseases: the natural course of diseases is not considered as AEs unless it develops intoa new diagnosis. Abnormal results of laboratory examinations: there are three occasions in which abnormal results are regarded as AEs, along with clinical symptoms or signs, the need of implementing medical intervention, clinically significant. Repeating AEs: it is necessary to report another AE once a disappeared or recovered AE happens again. The original data should be clear, concise, complete and accurate if AE terms are coded with MedDRA terminology. Conclusion The standards of AE reporting should be specified in study protocols and conduct trainings before starting a trial in order to unify the reporting standards and improve the quality of original data.

Key words: clinical research, adverse events, reporting standard, data quality