The pharmacokinetics of the commonly used drugs in kidney and liver dysfunction is to be known to all treating physicians. Most of the drugs are eliminated via urine or bile. Drugs causing toxicity to these eliminating organs (kidney, liver) require dosage adjustment. Some effects of the drug are measured by their plasma drug levels and this will give a hint regarding the patient compliance and also the toxicity. This chapter will highlight the important changes in sepsis, liver and kidney dysfunction, and drug dose adjustment required in liver and kidney diseases.