Background: Flavoured cigarettes are popular in Mexico. We examined how cigarette packaging design features used to communicate flavour influence perceptions of appeal, harm, perceived interest and pack preference among Mexico City residents. Methods: We conducted an experimental survey. Participants aged 13-34 years were randomly assigned to one of three conditions, viewed packs with systematically manipulated design features (colour, capsule image and flavour name) and answered questions on appeal, perceived harm, perceived interest and pack preference. Data were analysed using mixed effects and conditional logistic regression. Results: 1500 adolescents and 950 adults participated. Regardless of flavour, cigarette packs with a background colour and capsule image were more appealing to adolescents (OR=13.19, 95% CI 11.53 to 15.10; OR=1.68, 95% CI 1.45 to 1.88) and adults (OR=4.18, 95% CI 3.73 to 4.69; OR=1.66, 95% CI 1.49 to 1.85) than packs without. Among adolescents, 'Tropical Burst' named packs were more appealing (OR=1.43, 95% CI 1.20 to 1.72) than packs without a flavour name and among adults, 'Arctic Air' named packs were more appealing (OR=1.20, 95% CI 1.02 to 1.14). Adolescents and adults reported a preference for trying packs that displayed a flavour name, background colour or capsule image (b=0.104, b=0.702, b=1.316, p<0.001 and b=0.126, b=0.619, b=0.775, p<0.001). Conclusions: Colours and flavour capsule images appeal to adolescents and adults in Mexico. Mexico should consider adopting plain packaging to reduce appeal and interest.