Ethambutol is one of the first line drugs for treating tuberculosis. Its toxic effects on the optic nerve are majorly classified as reversible. However, worsening of vision and permanent vision loss after ethambutol discontinuation is also documented. To determine the effect of ethambutol toxicity on oligodendrocytes at different periods of treatment. Twenty-five male adult wistar rats of 110-130g average weight were housed in cages, exposed to 12-hour of dark and light cycles. After one week of acclimatization, five animals were randomly selected and sacrificed prior to ethambutol treatment for the control group (week 0). The remaining 20 animals were each orally administered 100mg/kg/day ethambutol. Five animals were randomly picked and sacrificed at the end of first, second, third, and fourth week of ethambutol treatment. There was no statistically significant difference in the number of oligodendrocyte cells obtained at the different stages of ethambutol treatment. Oligodendrocytes are not vulnerable to ethambutol toxicity for at least one month and they play a key role in reversing ethambutol induced neuropathy through myelin sheaths reconstruction. Key Words: Ethambutol, Oligodendrocytes, Optic Nerve, Optic Neuropathy.