Sinusoidal rotation and rotational stimulation tests were used to examine vestibular function in guinea pigs. The results showed that there was no statistically significant difference in the mean number of nystagmus of semi-cycle sinusoidal rotation test and the duration of nystagmus of rotational stimulation test for both the control and test groups before treatment in albinos and pigmented guinea pigs. Meantime, daily subcutaneous injection of gentamicin 125 mg/kg body weight for 12 days in albinos and pigmented guinea pigs showed no significant change in vestibular function until the 7th day of treatment. Significant impairment of vestibular function was noticed on the 10th treatment day. At 5 days after treatment vestibular impairment reached its maximum and minimal recovery was seen at 14 days after treatment. No Further improvement of vestibular function was noticed three months after treatment. The methods are feasible and reliable.