Whole-body cryotherapy (WBC) is one mode of cold therapy, during which patients are exposed to very cold air (-110°C) in minimal clothing. It is mainly used to alleviate inflammation and pain in arthritis, osteoarthritis, and for pain relief in fibromyalgia. Because severe cold exposure may be harmful for patients having other types of chronic diseases, such as cardiac or respiratory illnesses, we have carried out a series of studies examining the acute and long-term physiological effects of WBC in healthy humans (Westerlund et al. 2003, Smolander et al. 2004, Westerlund et al. 2004). The aim of the present study was to examine lung function before and after an acute exposure to WBC, and whether there are changes with repeated exposures. Eighteen females and 7 males (age 22-67 years) participated in the study. They were all healthy and non-smoking. The subjects had three 2 min exposures/week to the WBC for 3 months in a specially built, temperature-controlled unit (Zimmer, Elektromedizin). During WBC, they wore a bathing suit, surgical mask, cap, gloves, socks and shoes. Each subject performed maximal forced exhalations before and after the WBC (at 2 and 30 min) with a pneumotachograph-based system according to clinical standards. Peak expiratory flow rate (PEF) and forced expiratory volume in 1 s (FEV1) were determined from the flow-volume recordings. The study protocol followed the Helsinki Declaration. The data were analysed with ANOVA for repeated measures. The values of PEF and FEV1 measured before the WBC did not change during the 3 months, and the values were in the reference zone for healthy lung function. The PEF values after 2 min of the WBC were not significantly different from pre-exposure values. 30 min after the WBC the PEF values were slightly lower compared with values before the WBC, and the reductions were significant (p0.05) reduced 30 min after the WBC, but no other changes were observed during the study. The WBC did not cause any significant changes in FVC during the study. It was concluded that the WBC of short duration causes a slight strain on the respiratory system in subjects with healthy lungs. However, the WBC should be applied with caution in susceptible individuals.