The present invention is concerned with a method of distance protection of parallel transmission lines applicable both to series compensated and uncompensated electric power lines, using a distance relay. The method is characterized in that a pair of flags (ff1, ff2) are calculated for indication faulted and healthy circuits in parallel lines and in the same time a flag (Internal_Fault) for indication internal or external fault in parallel lines is calculated independently. Next gathering all calculated flags (ff1, ff2, Internal_Fault) an analyze of the value of these flags are performed and depending on the values of flags (ff1, ff2, Internal_Fault) and on their reciprocal relationship, a trip permission signal from the protection relay (4) is released and sent to the alarms devices or to the line breakers, or a block signal from the protection relay (4) is generated and sent to protect parallel lines before damage.