The pharmacology and toxicology of tobramycin in animals and humans are reviewed. After intramuscular and intravenous administration, tobramycin diffuses throughout most body tissues and tissue fluids. Therapeutic concentrations can be obtained by intravitreal or intradural injections. Dogs tolerate intracisternal doses of 0.2 mg/kg without adverse reaction. The half-life of tobramycin in cochlear fluid of guinea pigs and in renal tissues of rats is significantly longer than the serum half-life in these species and is reflected in the ototoxic and nephrotoxic potential of tobramycin and other aminoglycosides. In man, the serum half-life of tobramycin is 2 hr; renal clearance, apparent volume of distribution, and recovery from urine are similar to those parameters for gentamicin. The serum half-life in neonates in prolonged (4.5-8.7 hr). Concentrations of tobramycin in serum are effectively reduced by hemodialysis, but peritoneal dialysis is less efficient in elimination of the antibiotic. Tobramycin crosses the placenta and is concentrated in the kidney and urine of the fetus.