Objectives To describe and quantify the dengue-related knowledge, attitudes and practices of residents in an urban shantytown in Lima, Peru. Design/setting A cross-sectional survey of adults between 18 and 80 years living in approximately 120 blocks in Oasis, an urban shantytown situated in the low-to-middle income district of Villa El Salvador in Southern Lima. The survey was adapted from an existing survey previously used in Iquitos, Peru, and included questions relating to knowledge of dengue symptoms, transmission, prevention and current mosquito control practices. Participants A total of 240 surveys were completed with 80% of respondents being female and approximately 50% of all respondents describing themselves as housewives. Results Although 97.9% of respondents had heard of dengue, only 6.2% of people knew someone who had experienced the disease. Approximately half (54.2%) of the respondents knew dengue was transmitted by mosquitoes and 51.7% were able to identify fever and one other correct symptom of dengue. Female sex was significantly associated with greater symptom knowledge (OR 2.22, 95% CI 1.08 to 4.72) and prevention knowledge (OR 2.12, 95% CI 1.06 to 4.21). Past or current higher education attendance was significantly associated with symptom knowledge (OR 2.56, 95% CI 1.25 to 5.44) and transmission knowledge (OR 3.46, 95% CI 1.69 to 7.57). Knowledge of dengue was not significantly associated with carrying out practices to control mosquitoes (OR 1.76, 95% CI 0.87 to 3.54). Conclusions This population demonstrated baseline dengue knowledge. However, this was incomplete and substantially less when compared with endemic areas. Given the sporadic nature of dengue transmission in Lima, it is not surprising that knowledge of the disease was not associated with carrying out practices to reduce mosquitoes. However, as dengue transmission in Lima is likely to increase, understanding how best to improve public knowledge of the disease and how to translate this into appropriate community action will be a key public health consideration.