This study aimed to analyze the effects of isoflavones from Merr (soy) used topically as a vaginal gel on the induction of vascularization of the vaginal tissue in postmenopausal women. A placebo-controlled, randomized, double-blind trial was conducted with 22 postmenopausal women, randomly allocated for treatment with Merr isoflavone 4% vaginal gel daily for 12 weeks or with placebo gel for the same period. Vaginal microbiopsies were collected before and after the 12-week treatment. Immunohistochemistry analyses were performed to provide a blood vessel count per field in the vaginal tissue, pre and post intervention. The isoflavone group exhibited a significant increase in blood vessels per field relative to baseline, whereas the placebo group showed no difference compared to baseline. There was a significant difference in the increase of the number of blood vessels between the isoflavone and placebo groups. The results showed that local administration of Merr isoflavone gel promoted a significant improvement in the number of blood vessels in the vaginal tissue of postmenopausal women.