Whole blood surface tension of 15 healthy subjects recorded by the ring method was investigated in the temperature range from 20 to 40 °C. The surface tension σ as a function of temperature t (°C) is described by an equation of linear regression as σ(t) = (-0.473 t + 70.105) × 10-3 N/m. Blood serum surface tension in the range from 20 to 40 °C is described by linear regression equation σ(t) = (-0.368 t + 66.072) × 10-3 N/m and linear regression function of blood sediment surface tension is σ(t) = (-0.423 t + 67.223) ×10-3 N/m., J. Rosina, E. Kvašňák, D. Šuta, H. Kolářová, J. Málek, L. Krajči., and Obsahuje bibliografii