It is necessary to evaluate irrigation systems in order to determine their optimal performance, modify and manage them. In this research, five drip irrigation systems in Salas Babajani city located in Kermanshah province were selected and evaluated based on the instructions of the American Soil Conservation Service (SCS) and Merriam and Keller methods. The results of investigations showed that the wetted area ranged between 14.89 and 33.49 percent of the total area. The minimum and maximum values of water distribution uniformity in the investigated systems (EUs) were determined as 29.49 and 62.56 percent, respectively. The values of lower quartile application potential efficiency (PELQs) and lower quartile application efficiency (AELQs) of the systems fluctuated between 26.83 to 53.3 and 29.48 to 62.56 percent, respectively, which indicate the poor performance of the systems in all fields. According to Langiller Saturation Index (LSI) values obtained from water sources in the fields under study, in two fields, there was a tendency for calcium carbonate precipitation, but in other fields, there was no risk of precipitation. In general, the poor performance of the systems were due to various reasons, such as: not installing a central control station or a suitable filtration system, insufficient wetted area, inappropriate type and number of droppers, clogging of the droppers, pressure difference in the systems, inappropriate pressure and its uneven distribution, inappropriate distance and duration of irrigation and finally the poor management of exploitation.