Objective: Timely diagnosis of cancer is important for prognosis. Patients' health literacy (HL) may impact differences of diagnostic delays. Thus, we aim to explore the association between HL and diagnostic intervals in cancer.Methods: Questionnaire data were obtained from patients with cancer diagnosed in 2016 and their general practitioner (n = 3890). The primary care interval (PCI) and the diagnostic interval (DI) were calculated using dates from national registries and questionnaires. A long PCI and DI were defined as ≥75th percentile. HL was assessed using scales from the Health Literacy Questionnaire: engaging with healthcare providers (scale 6:Engagement, n = 3008), navigating in healthcare (scale 7:Navigation, n = 2827) and understanding health information (scale 9:Knowledge, n = 3002). Low HL was defined as a score ≤3.Results: Low HL was reported by 12.2% (Engagement), 27.0% (Navigation) and 9.3% (Knowledge) of the patients and associated with a long PCI after adjustment of socioeconomic factors: Engagement (prevalence rate ratio [PRR] 1.27 [95% CI 1.01-1.60]), Navigation ) and Knowledge (PRR 1.32 [95% CI 1.03-1.68]). No association was found between HL and DI.Conclusion: HL may interfere with the diagnostic processes in general practice.Efforts to manage low HL include GPs' awareness of patients' ability to explain and respond to bodily changes and use of corresponding safety-netting strategies.