Drug information supplying system by using computer (ACOS-630 model 10:NEC) named ゛On-line Hospital Formulary System" was newly developed in Kanazawa University Hospital. The special features of this system are 1) consisting of two types of datafiles, 2) three ways of retrieval including our original therapeutic code retrieval, 3) easy operation, and 4) short time required for maintenance of datafiles. The two types of datafiles are 1) basic information (e.g., dosage forms, adverse effects, precautions for administration) about the available drugs in our hospital and 2) the useful information for effective drug therapy made up by pharmacy staffs. Both datafiles are available to all medical and nursing staffs via computer terminals located in each nursing station and medical office. The maintenance of this system is well performed by pharmacy staffs. Data input and datafile maintenance are performed by on-line word processing software system, and time required for them is about six hours per month.