BACKGROUND: Prompt diagnosis of subarachnoid haemorrhage (SAH) is crucial to prevent life-threatening complications. However, timely SAH diagnosis is not uniformly achieved. This work aims to identify and analyse patient-reported reasons contributing to delayed SAH diagnosis. METHODS: We prospectively interviewed all patients with delayed SAH diagnosis at Wessex Neurological Centre, UK, between 1 May 2018 and 30 April 2021. Interviews were structured detailing symptom onset, healthcare consultations and reasons for delays. Content analysis was used to develop a coding scheme, and statistical analysis was performed using analysis of variance, χ2 and Fisher's exact tests. RESULTS: Of 550 cases of spontaneous SAH, 106 (19.3%) diagnoses were delayed.85/106 (80.2%) patients did not seek immediate medical attention (15.5% of all SAH). The most common reasons were 'waiting to see if symptoms would settle' (18/85, 3.3% of all SAH) and 'headaches not severe enough' (15/85, 2.7% of all SAH).48/106 (45.3%) reported diagnostic delays after seeking care (8.7% of all SAH), attributable to either misdiagnosis (36/48, 6.5% of all SAH) or errors in diagnostic testing (12/48, 2.2% of all SAH).Patients who did not seek immediate medical attention were more likely to experience diagnostic delays after seeking care (OR 9.77, 95% CI 4.97 to 19.49, p<0.001). Among patients presenting late, diagnostic delays after seeking care occurred more frequently in Glasgow Coma Scale (GCS) 15 patients compared with GCS <15 (OR 5.3, 95% CI 1.4 to 19.5, p=0.011). 49/85 (57.6%) patients who delayed seeking care, and 21/36 (58.3%) misdiagnosed patients reported clinical thunderclap headache. CONCLUSION: Prospective patient interviews capture data missed by retrospective chart review. This work has therefore identified important sources of delay in seeking care following the onset of SAH. Patients with delayed presentation were more likely to experience healthcare errors. These insights may help inform clinician awareness and public health initiatives aimed at earlier diagnosis.