Polygamy is common in most communities worldwide and widespread in many developing countries, especially in Sub-Saharan Africa and Asia. Similarly, in Ethiopia though the practice of polygamous marriage is prohibited it is practiced under customary law in all regional states. Similarly, to the country level in Lode HetosaWoreda polygamy is practiced under the garb of religion and customary laws. Notwithstanding the magnitude of the problem, there are limited local studieson polygamy. Cognizant of this gap, this study is attempted to investigate the lived experience of women in polygamous (particularly polygyny) marriage at Lode HetosaWoreda, Arsi Zone, Oromia Regional State. To meet the objectives of the study, qualitative approach with phenomenological design was employed. The study area and the participants were selected by using purposive sampling technique. To collect primary data, in-depth interview had been used. The collected data were analyzed byemploying thematic data analysis technique. The finding of the study revealed that personal related causes, socio-cultural causes and economic causesas the major causes that make women to enter into polygamous marriage. The study also identified some majorchallenges facing those women engaged in polygamous marriage.These challenges were: economic challenges, health challenges, psychological challenges, challenge from husband,sexual challenges and challenges from co-wives. The study also found out that economic and social benefits were the only opportunities that women enjoyed because of their engagement in polygamous marriage. To cope up theirchallenge, they used different mechanisms. The coping strategies include asking family support, using contraceptive method, discussing with co-wives, faith in God, joy in children, patience, living in different homesteads, living harmoniously with co-wives, accepting and respecting husband and his idea, being attractive and preparing delicious food. Based on the finding of the study,it was concluded that women in polygamous marriage had experienced a dozen of challenges but with limited benefits. Finally, it was recommended that the governmental and non-governmental organizations, religious leaders and community leader should have to work jointly to prevent the practice of polygamy in Arsi zone. Key words:Polygamy, Polygyny, marriage, women, lived experiences and Arsi zone