In this work the kinetics of volume changes of fluid spaces associated with infusion of Ringer’s solution are analyzed by using the single-fluid space model. During infusion of Ringer’s solution, the human body is assumed to be characterized by the single-fluid space model into which fluid is fed and from which fluid leaves. Various infusion types were tested to accommodate different medical situations. Volunteers were given Ringer’s solution and the changes in blood hemoglobin were detected. From the comparison with experimental data, the single-fluid space model was found to represent adequately the kinetics of human volume expansion during infusion of Ringer’s solution.