A 50-year-old female presented with complaints of progressive ataxia. Investigations showed a large intradural arachnoid cyst located anterior to the brainstem. Following marsupialization of the cyst she improved remarkably in her symptoms. The symptoms recurred nine months later and investigations revealed recurrence of the cyst. The cyst was evacuated again and two Teflon sponge sheets were placed such that they traversed the length of the cyst cavity and extended into the cisterna magna. At follow-up after 25 months, there has been no recurrence of symptoms or the cyst. The role and advantages of Teflon sponge in such cases is evaluated.