Previous studies have investigated a number of possible transport systems for the uptake of methylmercury (MeHg) in erythrocytes. In the present study, three additional systems were studied. The uptake of MeHg by isolated erythrocytes from rats was studied at 5ΨC and 20ΨC. Glutamine was used to test system N and system y + , and glycylglycine was used to test the oligopeptide-H + transport system. The Hill equation was used in kinetic analysis. The results show that both glutamine and glycylglycine stimulated the uptake of MeHg, but the stimulation by glycylglycine is stronger than by glutamine, and the stimulation at 5ΨC is stronger than at 20ΨC (mean values are 167.98% and 83.68% in the glycylglycine group at 5ΨC and 20ΨC versus 26.28% and 19.23% in the glutamine group at 5ΨC and 20ΨC). The kinetic analysis shows that: the Michaelis-Menten constant K m increased as temperature increased in both groups and was larger in experimental groups than in control groups; the Hill constants increased as temperature increased in both groups and were smaller in experimental groups than in control groups; and as temperature increased, maximum velocity V max increased in control groups and decreased in experimental groups, and was larger in experimental groups than in control groups, with the exception of the glycylglycine group at 20ΨC. The results demonstrated that system N, system y + and oligopeptide-H + transport systems were not involved in the in vitro uptake of MeHg into erythrocytes. The stimulation by glutamine and glycylglycine might be related to some signalling pathways, through which nitric oxide and oligopeptide serve as messengers and cause functional alterations in the uptake of MeHg.