Endemic relapsing fever (RF) is one of the most important arthropod-borne diseases caused by various types of Borrelia and transmitted by soft tick species. The investigation of the distribution of vectors in a region can help control and prevent the disease. This study aimed to investigate the distribution of Ornithodoros tholozani and Ornithodoros lahorensis in Iran and to identify the most influential climatic variables affecting their distribution. The ecological niche model was used in Maxent to predict the environmental suitability of the studied species. A review was conducted on the earlier studies carried out in Iran (1977-2018), and the coordinates of collection sites for these two ticks were recorded. Nineteen bioclimatic variables were used for the modelling. The main vectors of RF were reported from 13 provinces, 43 counties and more than 160 villages in Iran. The rate of Borrelia spp. infection was higher in O. tholozani (36%) than in other soft ticks. The annual mean temperature and precipitation seasonality were the most important factors affecting the distribution of RF vectors. The north-western regions of Iran were found to provide the best environmental needs for these vectors. Therefore, special attention should be paid to control the disease by managing contact with soft ticks in these areas.