BACKGROUND: The PRINCESSE project (11/2019-06/2023) implemented a sexual and reproductive health care package for female sex workers (FSWs) in the San Pedro area of Côte d’Ivoire. The package was offered through a mobile clinic operating on prostitution sites. A total of 489 women were included, but retention was low, with less than one-third attending quarterly visits. This analysis examines the factors that enable or hinder the adherence and retention of FSWs METHODS: A qualitative study, conducted between May 2022 and November 2023, involved 16 biographical interviews with participants, three individual interviews with non-participating FSWs, 10 interviews with participants who were lost to follow-up, and three focus groups. The analysis focuses on the FSWs’ perceptions of the benefits and constraints associated with their participation. RESULTS: FSWs reported that the mobile clinic’s presence on prostitution sites, the peer educators’ advanced strategies, and the site managers’ involvement in community mobilization facilitated their commitment to the PRINCESSE program. Additionally, the welcoming attitudes and skills of the care staff, the distribution of free condoms and lubricating gel, and the provision of free care and medication were reported to facilitate their retention in follow-up. However, some participants found certain aspects of the care provision burdensome, which limited their program adherence. These included concerns about excessive blood sampling and rumours of blood resale, the mobile clinic being located too far away and exposed to indiscretions, visits being deemed excessively long, and challenges related to the high mobility of FSW participants. Delays in the transmission of medical analysis results, incomplete coverage of expressed needs by the care offer, and insufficient quantities of condoms and lubricants hindered the retention of many participants. CONCLUSIONS: A paradox has arisen. Although the program was perceived to have benefits, it was deemed insufficient to meet the needs of FSWs and was seen as burdensome. Additionally, operational challenges have undermined participants’ confidence in the long term. However, the project was able to rely on its team, including caregivers and peer educators, which proved to be an essential factor in keeping FSWs engaged due to the close ties and trust established.