Wearing hospital gown (HG) as opposed to plain-clothes (PC) may contribute to the general state of inactivity of hospitalised patients. We designed a randomized study to determine the influence of clothing on the level of spontaneous physical activity (SPA) and to assess the length of hospital stay. Using triaxial accelerometry we measured the SPA in two groups of surgical patients, before and after an elective operation. Twenty eight patients received instructions to wear plain-clothes (group PC) during their stay in the hospital as soon as possible from a surgical point of view. Twenty-nine patients, serving as a control group, did not receive any specific instructions and as a result, were mostly wearing hospital gowns (group HG). Following the admission to the hospital, both groups showed a 50% decrease in SPA when compared to the recordings obtained during the last 24 hours spent at home. During the postoperative period, the SPA increased progressively in both groups. Although patients in group PC tended to be more active than those in the control group, the SPA was not significantly different (P = 0.4). Similarly, patients in group PC left the hospital 10 hours earlier than patients in group HG (P = 0.4). The power of our study was nevertheless low and a sample size of 700 patients might show statistically significant results. We conclude that wearing plain-clothes when hospitalized for elective surgery is not associated with complications and could be included in postoperative rehabilitation program.