The diaphragm is receiving renewed attention as a promising female-controlled method of preventing HIV and other sexually-transmitted infections. It is anticipated that female-controlled technologies will reduce women's biological susceptibility and assist in counteracting their sociocultural vulnerability to HIV. Understanding the subjective experiences of diaphragm users in different settings has the potential to inform the development and promotion of such methods. This paper explores the perspectives of female sex workers and women attending sexual and reproductive health services in Mombasa, Kenya. Data are reported from focus group discussions and in-depth interviews with women and men, following a prospective study investigating diaphragm continuation rates over six months. Discussions highlighted covert use of the diaphragm, during sex work or with casual partners, and coital independence as favourable attributes. These features were especially pronounced compared with male condoms. Few difficulties with diaphragm use were reported, although its insertion and removal occasionally presented problems. Many women - especially those in long term partnerships - wished to disclose its use but found the disclosure process highly problematic. Accidental discovery often resulted in partner conflict. Although future uptake of the diaphragm may be high in this setting, its use may be limited to certain types of relationships and relationship context.