Eighteen women with cervical ectropion and 12 women with ectropion and vaginal discharge were treated by cryosurgery. Evaluation of the cervical mucus characteristics by cervical score and in vitro penetration test was performed before treatment and 2 months later. In the group with ectropion only (group A) the total cervical score was 5.7 +/- 0.4 and 11.9 +/- 0.06 (P less than 0.001) (mean +/- standard error) before treatment and 2 months later, respectively. In the group with ectropion and vaginal discharge (group B) the total cervical score before and after cryosurgery was 3.8 +/- 0.4 and 11.8 +/- 0.1 (P less than 0.001), respectively. In vitro penetration tests in group A before and after treatment were 0.72 +/- 0.1 and 2.9 +/- 0.08 (P less than 0.001), respectively. In group B, in vitro penetration tests before and after cryosurgery were 0.25 +/- 0.1 and 2.8 +/- 0.1 (P less than 0.001), respectively. It appears that cryosurgery improves the cervical mucus characteristics. It is recommended that infertile patients with hostile cervical mucus and ectropion will be treated by cryosurgery.