Using the intrinsic optical signal the present study aimed to investigate changes in blood flow at the nasal epithelium in response to specific olfactory stimulation. Recording equipment included an endoscope, a CCD camera, and a light source of 617 nm. Two concentrations of the specific olfactory stimulant H(2)S (2.8 and 5.6 ppm), generated by a computer-controlled olfactometer, were used for olfactory stimulation. Eight healthy normosmic volunteers participated. Using 5.6 ppm H(2)S stimuli, responses were typically recorded from the olfactory cleft, middle turbinate, and middle meatus while responses were less pronounced for 2.8 ppm H(2)S stimuli. Response areas were significantly larger for the 5.6 ppm H(2)S stimuli. While further experiments are needed, recordings of the intrinsic optical signal may be used to obtain responses from the nasal cavity to specific olfactory stimuli.