Acrolein is a highly reactive, unsaturated aldehyde present in both indoor and outdoor air. It is considered a risk factor for indoor air health problems. The aim of the study was to investigate time-dependence and individual variation in sensory irritation from acrolein during controlled exposure. Participants (n=40) were exposed twice in an exposure chamber for 15 min, once to heptane and once to acrolein and heptane. The concentration of acrolein was set to 0.35 mg/m3. Sensory irritation in the eyes, nose and throat were rated continuously during exposure. Sensory irritation was detected in a time-dependent manner, but only in 70% of the participants. The results suggest that individuals who report relatively high levels of perceived stress are more vulnerable in developing symptoms due to certain indoor air exposures. Sensory irritation is an important endpoint in indoor air quality investigations.