OBJECTIVE: The use of traditional medicine and complementary alternative medicine (TM/CAM) derived from herbal remedies or natural supplements is increasing worldwide, but there are limited data on the use of TM/CAM during pregnancy. Iran has various ethnic populations, and the usage of TM/CAM by the different ethnic groups has not been researched. The aim of this study is to understand the use of TM/CAM modalities in pregnant women of different ethnic groups in southern Iran. METHODS: This study was conducted in primary health care centers in Khuzestan Province, Iran, from May to August, 2016. A semi-structured valid questionnaire was used to gather information in pregnant women (n = 170). RESULTS: About 46.5% of women in this study used TM/CAM during previous pregnancies. The majority (67%) of study participants were Arab. The Arab population showed increased use of TM/CAM during pregnancy (P = 0.014). Women with complications in former pregnancies had significantly higher incidence rate of TM/CAM use (65.8%) compared to the other group (39.6%) (P = 0.001). CONCLUSION Understanding TM/CAM use and the associated factors in different ethnic groups of pregnant women will benefit the evaluation of the proper health policies and mother-infant health programs. This study contributes to the growing literature on TM/CAM, ethnic diversity and pregnant women.