The use of a Langmuir probe in the study of an electric plasma is restricted to probes with a flat collecting area. For probes with other shapes a saturation of the ion current is not obtained. Since the electron probe current is made up, in part, of an electron equivalent of the saturated ion current, a knowledge of its value is necessary for probe analysis. A method of approximation is proposed by which this difficulty can be surmounted. In this method log i + log (1 + i'/i) is substituted for log i_e. Experimental results show that the method can be used and is applicable to all shapes of probes.