329 females with regress of low-grade dysplasia were followed up by annual vaginal smears for a maximum of 14 years. 53 developed recurrence of dysplasia. The average annual risk of recurrence was greatest 2-4 years after regress, being 4.3%. The average annual risk of recurrence for those followed up for more than ten years was 0.5%. None of the females developed cervical cancer. It is concluded that annual controls may prevent females with regress of previous low-grade dysplasia from developing cancer. After ten years with no further dysplasia, the females are recommended to follow the general practice for persons without previous dysplasia or cancer.