The susceptibility of important pathogens to aminoglycosides was analysed using data from five studies encompassing different patient groups. Enterobacteria were generally sensitive to all modern aminoglycosides without marked differences. The frequency of resistance of Pseudomonas aeruginosa and other non-fermenters to gentamicin was 5-15% and to amikacin was 0-3%, and similar values applied for staphylococci. A higher rate of resistance was observed in pathogens isolated from urological patients: for non-fermenters resistance to gentamicin, tobramycin and netilmicin was 24-28%, whereas resistance to amikacin was 12%; and for staphylococci resistance was 33% for gentamicin, 48% for tobramycin and 9% for netilmicin. It is concluded that resistance to aminoglycosides is not an important problem in the Federal Republic of Germany, probably because aminoglycosides are used in combination with beta-lactam antibiotics, except in the case of urinary tract infections. Aminoglycosides are still important antibiotics, thus their rational use and constant surveillance are necessary to preserve their efficacy.