The sexual behavior of older adults, especially women, has undergone changes in recent years, though there are still certain stereotypes today related to pathophysiology, beliefs, culture and tradition that negatively affect older adults’ sexual activity. The aim of our review is to present the main qualitative studies analyzing how physiological and psychosocial factors affect sexual behavior in older adults. A systematic review of these qualitative studies was carried out. All stages of this review were carried out peer-to-peer in order to guarantee minimized bias. A bibliographical search was completed between February and April 2019, in Web of Science, Scopus, PubMed Medline, PsycINFO ProQuest and CINAHL. To analyze the findings of the selected qualitative studies, a “Thematic Synthesis Analysis” was performed, using Eppi-Reviewer 4 software (UCL Institute of Education, University of London, UK). The quality of the studies was assessed with a CASP-Qualitative-Checklist. A total of 16,608 references were screened and 18 qualitative studies were included in this review. The studies involved 2603 participants across seven countries, most being women (approximately 80%). We identified a wide variety of physiological and psychological factors that can influence the sexual behavior of older adults, such as the presence of pathologies (erectile dysfunction and menopause), the strength of spiritual beliefs, and patriarchal roles upheld by upbringings conveying that women’s role is to provide men with sexual pleasure. Biological age in relation to stereotypical models of sexual behavior, emphasized as a risk factor in the contraction of sexual diseases, seems to play a relevant role as a factor limiting sexual behavior in older adults.