Blood flow in the cochlea, vestibular apparatus and facial nerve was investigated in the 12 temporal bones of 6 guinea pigs using non-radioactive microspheres. The cochlear blood flow volume was 1.80 +/- 0.82 microliters/min and the blood flow volume of the vestibular apparatus was 0.43 +/- 0.16 microliters/min. The blood flow volume of the facial nerve in the temporal bone was 0.29 +/- 0.17 microliter/min. Regarding these blood flow volumes, the difference between the right and left was not significant, although there were large interanimal differences. The distribution of the blood flow in the cochlea, vestibular apparatus and facial nerve is also described.