We assessed the short-term effects of hypertonic fluid versus isotonic fluid administration in patients with septic shock. This was a double-blind, prospective randomized controlled trial in a 15-bed intensive care unit. Twenty-four patients with septic shock were randomized to receive 250 mL 7.2% NaCl/6% hydroxyethyl starch (HT group) or 500 mL 6% hydroxyethyl starch (IT group). Hemodynamic measurements included mean arterial blood pressure (MAP), central venous pressure, stroke volume index, stroke volume variation, intrathoracic blood volume index, gastric tonometry, and sublingual microcirculatory flow as assessed by sidestream dark field imaging. Systolic tissue Doppler imaging velocities of the medial mitral annulus were measured using echocardiography to assess left ventricular contractility. Log transformation of the ratio MAP divided by the norepinephrine infusion rate (log MAP/NE) quantified the combined effect on both parameters. Compared with the IT group, hypertonic solution treatment resulted in an improvement in log MAP/NE (P = 0.008), as well as an increase in systolic tissue Doppler imaging velocities (P = 0.03) and stroke volume index (P = 0.017). No differences between the groups were found for preload parameters (central venous pressure, stroke volume variation, intrathoracic blood volume index) or for afterload parameters (systemic vascular resistance index, MAP). Hypertonic solution treatment decreased the need for ongoing fluid resuscitation (P = 0.046). No differences between groups were observed regarding tonometry or the sublingual microvascular variables. In patients with septic shock, hypertonic fluid administration did not promote gastrointestinal mucosal perfusion or sublingual microcirculatory blood flow in comparison to isotonic fluid. Independent of changes in preload or afterload, hypertonic fluid administration improved the cardiac contractility and vascular tone compared with isotonic fluid. The need for ongoing fluid resuscitation was also reduced.