Kallmann's syndrome is generally assessed by history and subjective tests of olfactory function. In this study three patients suffering from Kallmann's syndrome were investigated with more objective techniques, including the recording of chemosensory evoked potentials (CSEPs). After testing olfactory function by means of a simple odor identification test, anosmia was confirmed in only one patient, since the other two patients were able to distinguish between several odorants. However, investigations in which CSEPs were employed indicated that all three patients had complete loss of their olfaction as well as hypersensitivity of the trigeminal nerve. These findings prove the usefulness of CSEPs in clinical investigations of the sense of smell.