Effective communication between partners is crucial for good sexual health, but is often difficult to achieve. This qualitative study shows how gendered communication can act as an important barrier to successful dialogue between men and women. Both content and manner of speaking are often gendered: not only can topics of conversation be socially defined as more or less appropriate for a speaker according to his or her sex, but men and women can also differ systematically in terms of the phrases and words they use. This may lead to a lack of the common forms of expression that are needed for effective communication. The study examines communication about sexuality among young men and women in low-income areas of Mexico City. The relationship between gender stereotypes of sexual behaviour and the gendered nature of communication strategies is explored. The negative consequences of gendered communication for effective dialogue between men and women are illustrated. Interventions that can enhance communication between men and women would be expected to have a positive impact on sexual health. This paper argues that research and interventions intended to improve sexual health may instead inadvertently reinforce communication barriers not only by failing to address the social pressures that exacerbate gendered communication, but also more insidiously, by using language that actively contributes to these pressures. An example of an intervention that avoids this problem is the Mexican programme "Gente Joven" ("Young People").