This paper presents a simple and accurate photoelectric method for the determination of oxyhemoglobin (HbO₂), methemoglobin (MHb), and sulfhemoglobin (SHb) in a single sample of finger blood. The method involves measuring the optical density changes at specific wavelengths using a photoelectric colorimeter. For MHb, the absorption band at 635 mμ is used, while for SHb, the absorption band at 620 mμ is measured after converting MHb into cyanmethemoglobin (MHbCN). The concentration of HbO₂ is calculated by subtracting the concentrations of MHb and SHb from the total hemoglobin concentration. The accuracy and sensitivity of the method are evaluated through artificial mixtures, with errors typically not exceeding 0.2 gm per 100 cc for total hemoglobin and MHb, and about 0.1 gm per 100 cc for SHb. The method is also tested for the presence of extraneous pigments, showing that it remains reliable even in the presence of blue dyes. The authors conclude that the method is suitable for clinical use, particularly in diagnosing sulfhemoglobinemia and methemoglobinemia.This paper presents a simple and accurate photoelectric method for the determination of oxyhemoglobin (HbO₂), methemoglobin (MHb), and sulfhemoglobin (SHb) in a single sample of finger blood. The method involves measuring the optical density changes at specific wavelengths using a photoelectric colorimeter. For MHb, the absorption band at 635 mμ is used, while for SHb, the absorption band at 620 mμ is measured after converting MHb into cyanmethemoglobin (MHbCN). The concentration of HbO₂ is calculated by subtracting the concentrations of MHb and SHb from the total hemoglobin concentration. The accuracy and sensitivity of the method are evaluated through artificial mixtures, with errors typically not exceeding 0.2 gm per 100 cc for total hemoglobin and MHb, and about 0.1 gm per 100 cc for SHb. The method is also tested for the presence of extraneous pigments, showing that it remains reliable even in the presence of blue dyes. The authors conclude that the method is suitable for clinical use, particularly in diagnosing sulfhemoglobinemia and methemoglobinemia.