Kidney and liver are the major organs of metabolism and excretion of drugs. Renal and Hepatic impairment may affect the pharmacokinetics/pharmacodynamics and the safety of drugs. Adjusting the dosage based on organ function is the essential role of pharmacists. However, differences have been noted on the recommended dosage among the literatures. We compared and analyzed the recommendations of 4 literature sources which are commonly used for dosage adjustment. From April, 2011 to August, 2011, we selected data on recommendations for dosage adjustment for impaired renal and hepatic function of 100 drugs through a protocol. We analyzed the definition terms of renal and hepatic impairment, recommendations for dosage adjustment, evidenced references in four literature sources: Korean National Formulary (KNF), American Hospital Formulary System Drug Information (AHFS), Micromedex (MM) and Drug Prescribing of Renal Failure (DPRF). We further examined the data homogeneity by comparing how drugs that required no adjustment according to one source were categorized by the other. Sources use different definition terms among themselves except DRPF. Presence or absence of evidenced references about renal/hepatic functional states are KNF (0%/0%), AHFS (78%/62.6%), MM (87.5%/65.6%) and DPRF (93.2%/no recommendation) respectively. Recommendations of specific dosage and dosing interval are KNF (24%/13%), AHFS (39.6%/12.1%), MM (50%/17.7%), and DPRF (55.4%/no recommendation) respectively. Regarding the data homogeneity, the differences were remarkable. Drugs with no adjustment according to AHFS were categorized to be adjusted/ contraindicated by KNF, MM, DPRF and the values were (44%/5.6%), (22%/0%), and (36%/0%) in renal function, (39%/6.5%), (19%/3.2%), and (no recommendation/no recommendation) in hepatic function respectively. Our study shows remarkable definite variation in definitions and recommendations about definition terms, information of dosage and interval, presence or absence of evidenced references. Especially for KNF, quantitative recommendations on dosages and dosing intervals should be made in the near future. To maximize the drug effect and safety and to minimize the heterogeneity of the literature sources, reviewing at least two sources are suggested when recommending the proper dosage adjustment based on organ function.