Background: Parenteral fluids are commonly used in people with acute stroke with poor oral fluid intake. However, the balance between benefit and harm for different fluid regimens is unclear. Objectives: To assess whether different parenteral fluid regimens lead to differences in death, or death or dependence, after stroke based on fluid type, fluid volume, duration of fluid administration, and mode of delivery. Search methods: We searched the Cochrane Stroke Group Trials Register (May 2015), the Cochrane Central Register of Controlled Trials (CENTRAL), the Cochrane Database of Systematic Reviews (CDSR) and the Database of Abstracts of Reviews of Effects (DARE) (Cochrane Library 2015, Issue 5), MEDLINE (2008 to May 2015), EMBASE (2008 to May 2015), and CINAHL (1982 to May 2015). We also searched ongoing trials registers (May 2015) and reference lists, performed cited reference searches, and contacted authors. Selection criteria: Randomised trials of parenteral fluid regimens in adults with ischaemic or haemorrhagic stroke within seven days of stroke onset that reported death or dependence. Data collection and analysis: One review author screened titles and abstracts. We obtained the full-text articles of relevant studies, and two review authors independently selected trials for inclusion and extracted data. We used Cochrane's tool for bias assessment. Main results: We included 12 studies (2351 participants: range 27 to 841). Characteristics: The 12 included studies compared hypertonic (colloids) with isotonic fluids (crystalloids); of these, five studies (1420 participants) also compared 0.9% saline with another fluid. No data were available to make other comparisons. Delay from stroke to recruitment varied from less than 24 hours to 72 hours. Duration of fluid delivery was between two hours and 10 days. Bias assessment: Investigators and participants in eight of the 12 included studies were blind to treatment allocation, seven of the 12 included studies gave details of randomisation, and eight of the 12 included studies reported all outcomes measured. Results: There were no relevant completed trials that addressed the effect of volume, duration, or mode of fluid delivery on death or dependence in people with stroke. The odds of death or dependence were similar in participants allocated to colloids or crystalloid fluid regimens (odds ratio (OR) 0.97, 95% confidence interval (CI) 0.79 to 1.21, five studies, I2 = 58%, low-quality evidence), and between 0.9% saline or other fluid regimens (OR 1.04, 95% CI 0.82 to 1.32, three studies, II2 = 71%, low-quality evidence). There was substantial heterogeneity in these estimates. The odds of death were similar between colloids and crystalloids (OR 1.02, 95% CI 0.82 to 1.27, 12 studies, II2 = 24%, moderate-quality evidence), and 0.9% saline and other fluids (OR 0.87, 95% CI 0.67 to 1.12, five studies, II2 = 53%, low-quality evidence). The odds of pulmonary oedema were higher in participants allocated to colloids (OR 2.34, 95% CI 1.28 to 4.29, II2 = 0%). Although the studies observed a higher risk of cerebral oedema (OR 0.20, 95% CI 0.02 to 1.74) and pneumonia (OR 0.58, 95% CI 0.17 to 2.01) with crystalloids, we could not exclude clinically important benefits or harms. Authors' conclusions: We found no evidence that colloids were associated with lower odds of death or dependence in the medium term after stroke compared with crystalloids, though colloids were associated with greater odds of pulmonary oedema. We found no evidence to guide the best volume, duration, or mode of parenteral fluid delivery for people with acute stroke.