1 Plasma levels of gallamine and the elicited neuromuscular response have been measured in seven patients with compromised renal function who received a single 2 mg/kg dose and in a further patient who received an initial dose of 2 mg/kg followed by two additional doses of 1 mg/kg. 2 The plasma level-time data from all patients was adequately explained by a biexponential equation interpreted as a two-compartment open mammillary model. 3 Comparison of the model-independent pharmacokinetic parameters for gallamine between these patients and a group of normal patients revealed that the elimination phase half-life (T and one-half beta) was significantly prolonged in renal failure with a marked reduction in the plasma clearance of gallamine. 4 Gallamine had larger apparent volumes of distribution in the presence of renal failure than those found in normal patients. 5 The peak paralysis levels attained and the associated plasma concentrations of gallamine were similar in patients with and without renal failure. 6 At this low dosage the rate of recovery from paralysis in renal failure patients, though similar to that noted normally, appeared to be somewhat slower in some patients. 7. The results suggest that gallamine is not to be preferred to other nondepolarizing muscle relaxants in patients with renal failure.