AIM: To determine the incidence, risk factors and outcomes of delayed suprachoroidal haemorrhage (DSCH) after glaucoma surgery. METHODS: A retrospective case-control study was performed at a tertiary referral eye hospital on patients who presented with DSCH following glaucoma surgery. Cases were compared with a matched-control population that underwent equivalent procedures but did not develop DSCH. The main outcome parameters were incidence of DSCH, risk factors associated with its occurrence, visual outcome and prognostic factors. RESULTS: Of the 2752 glaucoma surgeries performed during the 10-year recruitment period, 29 cases of DSCH (1%) were identified. An increased incidence of DSCH was observed after glaucoma drainage device implantation compared with trabeculectomy-associated DSCH (p<0.0001; odds ratio 3.4; 95% CI 1.9 to 5.4). Risk factors for DSCH included low postoperative intraocular pressure (< or =3 mm Hg; p<0.001), aphakia (p<0.001), prior intraocular surgery (p<0.002), hypertension (p<0.001), anticoagulation (p = 0.002), ischaemic heart disease (p = 0.001) and respiratory disease (p = 0.008). The visual outcome of patients with haemorrhage was poor (logMAR 1.34 (SD 0.41)) and was significantly worse when compared with the control group (p = 0.002). CONCLUSIONS: In this study cohort, DSCH occurred more frequently after glaucoma drainage device implantation compared with trabeculectomy. Caution should be exercised when operating on patients with known ocular and systemic risk factors.