Background: During the last decades in Peru there have been greater demographic changes, like the remarkable increase in the number of cohabitating couples and the decrease of married ones. Therefore, this study aims to describe the perception of cohabitation and marriage between women in the city of Arequipa, Peru. Methods: 764 women between 18 and 66 years of age were randomly selected according to their socioeconomic level and they were surveyed with a questionnaire about cohabitation and marriage perception. The results indicated that the majority of evaluated women considered marriage important (82.5) because it is the most appropriate way to start living as a couple (35.2%) and it is a legally recognized institution (31.3%), among other reasons. Furthermore, the majority of women do not consider cohabitation as more convenient than getting married (65.8%) and mostly ...