The influence of the blade curvature of the disc turbine on the power consumption has been studied experimentally. Standard Rushton disc turbine is very often used for mixing of low viscosity systems. Recently, the authors of papers [1-3, 6, 7] have recommended disc turbine with modified shape of the blades for mixing of the gas - liquid systems. Blades in a modified version are curved in such a way that concave or convex turbines are created (Figs. 1a, 1b). Identically as for Rushton disc turbine, the parameters d, a, b, Z, and d(o) characterize geometry of such turbines. Additionally, the profile of the blade curvature is described by the radius R and the length O of the circular arc of the blade. As literature data show, the radius R is equal to b/2. Geometrical parameters of the stirrer affect, for example, the value of the power number Ne. The dependence of the power consumption on the geometry of the Rushton disc turbine can be evaluated from literature data [4, 5]. The blade curvature of the concave turbine may also affect the power number, however, this influence has not been studied till now. The aim of the research work was to investigate power consumption of the turbines with curved blades in the range of the geometrical parameter O is-an-element-of < piR; 3piR/2 > (Fig. 2). The measurements were carried out by means of the strain gauges technique for a baffled stirred tank of the inner diameter D = 0.45 m, filled with Newtonian fluid up to the height H = D. Other geometrical parameters were as follows: d/D = 0.33; a/d = 0.25; b/d = 0.2; Z = 6; R = b/2; h/D = 0.33; J = 4; B/D = 0.1. The experimental data Ne = f(Re) for the turbulent regime of the fluid flow (Re is-an-element-of < 10(4); 6.10(4) > were obtained. The results for different turbines are presented in the table. Power numbers for concave and convex disc turbines have been found as 1.94 and 1.58 times lower, respectively, than that for a standard disc turbine with flat blades. The dependences of the power numbers for concave and convex turbines on the geometrical invariant i(o/b), defined by Eq. (4), are shown in Fig. 3 and the table. The results of the investigations have proved that the influence of this invariant on the power consumption can be neglected in the range i(o/b) is-an-element-of < pi/2; 3pi/4 > (it corresponds to the parameter 0 is-an-element-of ).