Injection site-pain and bruising are common side effects of subcutaneous heparin injections. These adverse outcomes are problematic for both the patient and the nurse. Specifically, site-pain causes the patient discomfort and bruising limits possible sites for subsequent injections. It is important that nurses use an injection technique that minimises the incidence of adverse outcomes when administering subcutaneous heparin injections. This study examines the effect of duration of subcutaneous heparin injection on site-pain intensity and bruise size experienced by a group of patients being treated with heparin for ischaemic stroke or transient ischaemic attacks.A quasiexperimental design with subjects serving as their own control was used to address the study objectives. The independent variable was the duration of the injection and the dependent variables were site-pain and bruise size. A convenience sample of 34 subjects receiving 5000 units of a subcutaneous Fragmin injection twice a day were recruited from a large teaching hospital. Subjects rated the level of perceived site-pain intensity during injection using the vertical Visual Analogue Scale. Injection-site bruising was measured at 48 and 60 hours after injection. Data were analysed using the Wilcoxon Sign-Rank test. Results indicated that injection technique B (30-second injection duration) resulted in significantly less intense site-pain during administering the injection and fewer and smaller bruises.The findings of this study indicate that injecting subcutaneous heparin over a longer duration may reduce injection site-pain and bruising.