During 4 years, 1980–1984, 197 patients were treated for CIN II and CIN III by cryosurgery. Included were 62 patients with endocervical involvement (positive ECC). The cure rates of a single cryosurgical treatment were lowered significantly by increasing grade of CIN and by endocervical involvement. The factors influencing the cure rates of cryosurgery are discussed in relation to the results obtained in the present study. The most important step in treatment of patients with CIN by conservative methods seems to be the pretreatment evaluation and not the method of treatment. Despite the fact that we achieved good results in treating patients with CIN II and endocervical involvement (cure rate: 88.9%) it is our opinion that endocervical involvement should contraindicate conservative procedures. The potential risk of overlooking invasive disease among these patients should always be kept in mind. Careful pretreatment evaluation in patients undergoing cryosurgery is mandatory, or else this excellent method would be brought into discredit.