Somatosensory Evoked Potentials by stimulation of the trigeminal nerve (TSEPs) were recorded from 30 healthy subjects (15 males, 15 females; mean age: 45.2 years; range: 21-66 years) in order to assess normative data for clinical purposes. To elicit the TSEPs, electrical square pulses (duration: 0.1 msec; frequency: 3.3 Hz; intensity: 4-6 mA) were delivered by bipolar skin electrodes (cathode over the foramen mentale and anode on the middle of the chin, stimulating the trigeminal third branch). TSEPs were obtained from C3-Fpz and C4-Fpz by twice averaging 1000 responses. Time base was 100 msec; bandpass filter setting was 5-1500 Hz. In our normal subjects the TSEPs were composed of several components (N1, P1, N2, P2 and N3); the components, with the exception of N3, were always bilaterally detectable. Statistical analysis (repeated measures analysis of variance) demonstrated a dependence of TSEP latencies on sex; it did not demonstrate an analogous dependence on either side of stimulation or age. Finally, we propose some guidelines for the evaluation of TSEPs: consider N1, P1, N2 and P2 waves, base the judgement of normality on latencies rather on amplitudes, use differing normative data according to sex.