Aim <p>Failures in diagnostic processes lead to avoidable patient contacts, diagnostic delays, and inefficient use of healthcare resources. Such failures in both diagnostic and treatment pathways represent a significant source of systemic inefficiency and preventable harm. This study aimed to identify health conditions in which diagnostic-related failure demand is particularly prominent and to explore how it manifests.</p> Subject and methods <p>This systematic review following PRISMA guidelines was registered in PROSPERO (CRD420251035554). Literature searches were performed in Ovid MEDLINE and Scopus in April 2025. Studies were included if they examined diagnostic-related failure demand associated with specific health conditions focusing on missed, delayed, or incorrect diagnoses. Studies from diverse countries and healthcare systems were included, and no geographic restrictions were applied. Studies lacking disease specificity or addressing only patient- or system-level factors were excluded. Key variables included the number of prior healthcare contacts, average diagnostic delay (in years), frequency and nature of misdiagnoses, treatment availability and cost-effectiveness, and symptom patterns.</p> Results <p>A total of 38 studies covering 33 health conditions were included, encompassing both common and rare diseases. Ten conditions were reported as more prevalent in women and three as more common in men. Patients had multiple healthcare contacts prior to diagnosis, with delays ranging from &lt; 1 year to &gt; 30&#xa0;years.</p> Conclusion <p>Diagnostic-related failure demand was observed across diverse conditions and associated with reasoning biases, limited clinical awareness, and structural barriers within healthcare systems. An improved symptom recognition, a strengthened clinician education, and digital tools such as artificial intelligence may support earlier diagnosis and more efficient care pathways.</p>