Abstract Misconception and contraception: knowledge and decision-making in contraceptive consultations with a language barrier Just like in general medical consultations, different domains of knowledge come together and are negotiated in contraceptive consultations, followed by decision-making on the contraceptive method. Research shows that a language barrier can hamper knowledge negotiation and decision-making in medical consultations. Our paper contributes to those findings by focussing on contraceptive counselling as a specific and underexplored consultation type. We gathered our data in a Belgian abortion clinic, where contraception is discussed during the consultations, and where an important part of the consultations are characterised by a language barrier. We adopt a Bourdieusian view on language as capital, and use a linguistic ethnographic and interactional sociolinguistic approach, complemented with analytical tools from conversation analysis on epistemics and deontics. The analysis of data fragments, ranging from a limited to a double language barrier, shows that this barrier is connected in various ways with how, and how much, knowledge is negotiated. Incomplete renditions, interruptions, epistemic and deontic claims from non-professional interpreters, along with a lack of shared contextualisation, impede clients to gather information and therefore influence decision-making. We conclude that a language barrier involves a potential risk for knowledge negotiation and decision-making in contraceptive consultations. More attention from healthcare professionals to language barriers could empower women in their sexual and reproductive health choices.