The case series consists of 106 women consecutively collected during 1968 to 1973 from those with a vaginal smear belonging to Papanicolou's groups III and attending the gynaecological department in Umeå. Probably the series is a fair random sample of the population (congruent to 150,000 people) of the area served by the clinic. The extension of the colposcopically delimited atypical transformation zone (with its upper bordèrline against normal cervical villi) in most cases being small, the surgical procedure--a small cone congruet to ring biopsy--was accordingly insignificant. In 9 cases only a large conization was performed. As only a small part of the cervical tissue was usually removed it is probable that the enzymatic and mechanical properties of the cervix as well as its capacity as a sperm reservoir could be preserved. The median of the observation time is 26 months, range 3 months to 5 years. At the follow up the colposcopic and histological picture has so far shown no sign of atypia in 91 subjects. The same applies cytologically to the patients subjected to a large conization. Two women have moved away from the district. A relapse occurred in 4 patients, who after a large conization have remained cytologically negative. Throughout the investigation the term a typia has been used to characterize the cytological, colposcopic and histological changes, the degree and extension of this atypia being taken into considertion. Thus the abstruse nomenclature in common use is avoided. Cytological atypia is cellular in character, while histologically it includes the degree of structural derangement of the epithelial architecture as well. Colposcopically the angioarchitecture and the capillary distance seem to be the most important features. The correlation between the colposcopic and the cytological and histological findings is high when the degree of atypia is marked. It is inferred, therefore, that the descriptive term atypia should replace the superfluos bulk of terms in the fields in question.