It is common practice in clinical therapy to use the aminoglycoside group of antibiotics to treat infections caused by Gram-negative organisms in end-stage renal disease (ESRD) patients who are undergoing haemodialysis (HD). Tobramycin, amikacin and, to a lesser extent, gentamicin and netilmicin are the drugs most frequently administered. However, as this type of treatment involves complex problems of dosage, partly because of the numerous factors involved in determining the dosage, and partly because of the narrow therapeutic range of these antibiotics, some complex pharmacokinetic adjustments have to be carried out in order to avoid adverse reactions and to maintain the minimum therapeutic levels of these drugs. To solve these problems, a multifactorial study was carried out using the various parameters involved in these processes in order to develop a simple graphical approach. Using this system of graphs, the loading and maintenance doses of these antibiotics can be predicted, obviating the need for complex calculations. The approach was checked by applying it to the analysis of dosage regimens in ESRD patients undergoing HD being treated with tobramycin and amikacin. It was found that after the administration of the loading and maintenance doses calculated using this approach, plasma concentrations correctly situated within the therapeutic range of these antibiotics [maximum and minimum therapeutic drug concentrations (Cmaxand Cmin)] were achieved, in contrast to those obtained when administering the doses recommended in antimicrobial therapy for these cases.