The study aimed to investigate the volume of the olfactory bulb in smokers. Specifically, we wanted to see whether environmental influences may exert a negative influence on OB structure. Twenty-one smokers and 59 non-smokers, matched for age and sex, underwent olfactory testing by means of the Sniffin' Sticks testing device (measurement of odor threshold and identification abilities). In addition, they underwent an MR scan with 2-mm-thick T2-weighted fast spin-echo images without interslice gap in the coronal plane covering the anterior and middle segments of the base of the skull. Olfactory function was not different between the 2 groups; however, olfactory bulb volumes were smaller in smokers than in non-smokers (p = 0.006). The deficit seen at the level of the OB did not correlate with the duration of smoking. The current data indicate that smoking may have a negative effect on the olfactory system before this becomes obvious in terms of a decreased olfactory function.