The safety and efficacy of abrasive cytology, using the cytobrush, were evaluated in 300 pregnant patients. When compared to conventional cytology obtained with a cotton-tipped applicator there was no difference in adverse pregnancy events. Smear adequacy (containing endocervical cells) was statistically (P less than 0.01) and clinically increased from 21 to 86%. The use of abrasive cervical cytology was associated with a twofold increase in the incidence of abnormal smears.