Objective: To describe the knowledge of primary teachers from Chiclayo on the attention deficit and hyperactivity disorder (ADHD) during 2015. Material and methods: Cross-sectional design. Single-stage cluster sampling. A questionnaire validated by experts and pilot test was used. Univariate analysis was performed and an exploratory bivariate analysis using Stata 12. Results: 434 teachers were interviewed: 211 (48.6%) of private schools and 223 (51.4%) of public: The mean age was 39 years. 74.1% of the teachers believe that ADHD "is a major problem for the child", 42.1% that "drug treatment is addictive", 32.5% that "it can be caused by sugar and other food additives"; 29.6% that is caused by "bad parenting and parental abuse" and 8.1% that "It is so prevalent that may be an invention of the doctors". When comparing public and private schools, differences were found in the response to these false statements, "students with ADHD should receive less homework than children without this problem", 39.8% versus 24.6% (p = 0.001) "Students with ADHD should be evaluated orally only" 34.1% versus 18.8% (p = 0.000), "the pharmacological treatment of ADHD is addictive" 49.3% versus 34.8% (p = 0.002). Teachers with less years of experience had higher frequency of correct answers. Conclusions: The knowledge of primary teachers from Chiclayo in relation to ADHD is higher than those found in other studies but still insufficient.