The effects of nitroglycerine (NTG) are mediated by liberated nitric oxide (NO) after NTG enzymatic bio-transformation in cells. The aim of this study was to evaluate some products of NTG bio-transformation and their consequences on the redox status of rat erythrocytes and reticulocytes, considering the absence and presence of functional mitochondria in these cells, respectively. Rat erythrocyte and reticulocyte-rich red blood cell (RBC) suspensions were aerobically incubated (2 h, 37 0C) without (control) or in the presence of different concentrations of NTG (0.1, 0.25, 0.5, 1.0 and 1.5 mM). In rat erythrocytes, NTG did not elevate the concentrations of any reactive nitrogen species (RNS). However, NTG robustly increased concentration of methemoglobin (MetHb), suggesting that NTG bio-transformation was primarily connected with hemoglobin (Hb). NTG-induced MetHb formation was followed by the induction of lipid peroxidation. In rat reticulocytes, NTG caused an increase in the levels of nitrite, peroxinitrite, hydrogen peroxide, MetHb and lipid peroxide levels, but it decreased the level of the superoxide anion radical. Millimolar concentrations of NTG caused oxidative damage of both erythrocytes and reticulocytes. These data indicate that two pathways of NTG bio-transformation exist in reticulocytes: one generating RNS and the other connected with Hb (as in erythrocytes). In conclusion, NTG bio-transformation is different in erythrocytes and reticulocytes due to the presence of mitochondria in the latter.