The insurance industry due to its mission is considered one of the important and basic industries in the country, and it is very important to determine and recognize the current performance of companies in this industry in order to provide the basis for continuous improvement while evaluating their performance compared to other companies. One of the performance evaluation criteria is return to scale, so that by recognizing it, it is possible to create a basis for improving the performance of companies. Therefore, the present study is aimed to investigate whether there is a relationship between returns to scale and company size in Iranian insurance companies or not. For this purpose, first the technical efficiency condition is calculated using three CCR, BCC and NIRS models, and then, return to scale of insurance companies is extracted with the Fare and Grosskopf method in three periods of 2017, 2018 and 2019. The comparison of the returns to scale of companies with their size indicated that the majority of companies in the industry operate with increasing or decreasing returns to scale and in all three periods only 15% of companies have constant returns to scale. Also, the results of the calculations showed that the insurance companies with small and medium market value have increasing returns to scale; thus, there is a potential to grow and expand their activities. Also, the increasing returns to scale in such companies are incentives for small and medium-sized companies to merge and take benefit of better cost economies. پرونده مقاله