A 7.5-month pregnant Holstein heifer was brought to our clinic as having a prolapsed vagina. Examination showed a unilateral Bartholin gland cyst on the left side of the vagina. The cyst was punctured, drained, and cleaned with lotagen. No active reproduction was found in the microbiological culture of the cyst contents, but in the biochemical analysis found that albumin was found high. Although this problem is more often seen in cows which are old or had undergone dysctocia, and no certain cause was found in this case.