OBJECTIVE:To understand the knowledge about rational drug use(RDU) in inpatients.METHODS:An cluster sampling investigation was carried out by questionnaire at separate times and in separate groups in 2 419 inpatients in the hospital where the authors work. RESULTS:The majority of the inpatients were concerned much with the drug use,but lacked the knowledge about RDU and had much misunderstanding about drug use.CONCLUSION:The relevant measures must be taken to guide the RDU in patients and to improve the understanding of RDU.