The characteristics of lightning overvoltages initiated on overhead distribution lines vary greatly depending on the lightning stroke characteristics, the method of overvoltage generation (direct or induced), the orographic conditions (shielding effects) and the configuration of the line (medium or low voltage line, insulation level, presence of neutral conductors, earth resistance of the neutral etc.). In this paper the main characteristics of lightning overvoltages were clarified, as well as tools provided for the prediction of the number of lightning strokes to the lines. Waveshapes and peak-values of lightning overvoltages due to direct or indirect strokes have been described as well as their dependance on the line configuration, both for MV and LV networks. Since it is necessary for the Power utilities to protect their distribution networks in order to minimize the customers outages and the distribution apparatus damage caused by lightning, the information given in this paper consists of the basic knowledge which is helpful for the distribution engineers in order to determine the proper specific measures they have to take for this purpose in their LV and MV networks