We investigated whether dirhinal olfactory thresholds differ from monorhinal ones. Experiments 1 and 2 investigated butanol, Experiment 3 phenylethylalcohol. In Experiments 2 and 3 pen-like odor dispensing devices it-ere used, in Experiment 1 odors were presented in glass bottles. Participants were in excellent health (Experiment 1: 14 female [f], 15 m [m], mean age [ma] 24 years; Experiment 2: 12 f 19 m, ma 24 years; Experiment 3: 19 f 19 in, ma 32 years). Thresholds were assessed for left, right, and both nostrils. No significant difference was found between dirhinal results and results for the best of two nostrils. Apart from this, thresholds were found to improve with repeated testing. In conclusion, using two odorants with different techniques of administration in studies performed at different sites, the present results indicated that there is no major difference between odor detection thresholds obtained for the best and both nostrils.