The implementation of clinical pharmaceutical care and documentation of the intervention activities done by pharmacist not only improve the drug safety and cost effectiveness, but have considerable help on the pharmaceutical care services analysis. Therefore, it is important to have an appropriate drug-related problems classification instrument for the quality improvement of pharmaceutical care process and clinical research. This article will introduce a regularly revised and verified classification system -- the PCNE drug-related problems classification, which has been applied in pharmacy practice and research. Moreover, the difference among current and previous versions will be reviewed to provide hospital pharmacists the opportunity to introduce the system into clinical practices.