Childhood Attention-deficit/hyperactivity disorder (C-ADHD) is a neurodevelopmental disorder, associated with an increased risk of subsequent schizophrenia. The objective of the present study was to determine the prevalence of C-ADHD in schizophrenia and the clinical and cognitive characteristics associated with C-ADHD history in schizophrenia. 569 subjects with schizophrenia (74 % men, mean age 30.8) were included in ten expert centers at a national level and tested with a comprehensive battery of clinician-rated, patient-reported scales and cognitive tests. C-ADHD was assessed with the WURS (Wender Utah Rating Scale) self-report questionnaire. Multivariate, correlation, and principal component analyses (PCA) were conducted. Thirty-nine subjects (N = 39, 6.9 %) were classified in the C-ADHD group. Compared to those without C-ADHD, subjects with C-ADHD were more frequently male, had lower education levels, more severe positive clinical symptoms, more subjective cognitive deficits complaints, and lower medication adherence with small to medium effect sizes. Two cognitive components emerged from the PCA, one component including perceptual reasoning and working memory, and another component including visuospatial search and graphomotor speed, cognitive inhibition/flexibility and central executive functioning. Both components were associated with lower performances in the C-ADHD group. C-ADHD is frequent in schizophrenia and associated with more severe positive symptoms and impaired cognitive performances compared to those without C-ADHD. This suggests that the pathophysiological mechanisms contributing to these disorders may lead to the worsening of the cognitive functioning in patients with both disorders. C-ADHD is a relevant clinical marker to discriminate subgroups of schizophrenia with different profiles for a precision-psychiatry approach.< Réduire