Background: The efficacy of decompressive craniectomy (DC) for patients with intracranial hypertension secondary to aneurysmal subarachnoid haemorrhage (aSAH) remains unclear. Methods: We identified aSAH patients who underwent DC following microsurgical aneurysm repair from a prospectively maintained cerebrovascular registry and compared their outcomes with a propensity-matched cohort who did not. Results: A total of 45 aSAH patients underwent DC between 01/09/2011 and 20/07/2020 and were compared with 45 propensity-matched controls. There were no differences in patient age (p=0.48), gender (p=0.53) or the proportion requiring endovascular vasospasm treatment (p=1.00). However, patients in the DC subgroup had a higher mean WFNS grade (3.47±1.53) compared with matched controls (2.8±1.25, p=0.03). Patients treated with DC had a higher rate of inpatient mortality (20.00% vs 0.00%, p=0.0025), unfavourable outcome (mRS≥4) at 1st (42.22% vs 11.11%, p=0.0016) and final (31.11% vs 2.94%, p<0.001) follow-up, and NIS-Subarachnoid Hemorrhage Outcome Measure positivity (40.00% vs 13.33%, p=0.0079). They also had a higher median mRS at 1st [3(2–4) vs 1(1–2), p<0.001], and final [2(1–4 vs 1(1 (0–2), p<0.001] follow-up. Conclusions: Patients treated with DC fared worse at every endpoint, which was disproportionate to the difference in presenting WFNS grade. These data do not support the use of DC following microsurgical clipping of a ruptured aneurysm.