To investigate the necessity, safety and acceptability of routine Papanicolaou (Pap) smear in pregnant women and cytological characteristics of the smears during pregnancy.Pap smear were performed in 954 pregnant women, 1,053 normal controls and 1,908 gynecological out-patients. The cytological preparations were analyzed by using PAPNET method and following Bethesda (TBS-NCI) diagnostic criteria. Quality control was carried out by following TBS-NCI standard.Abnormal epithelial change was found in 89 women (89/954, 9.3%) of pregnant group, which was quite similar to normal controls group and gynecological group. Occurrence rate of cervical squamous intraepithelial lesion (SIL) was the lowest in pregnant group (0.94%, 9 in 954 cases), comparing with control group (2.75%) and gynecological group (6.23%). However, pregnant group had the highest infection rate (89.9%), as compared to gynecological group (64.5%), and normal controls group (69.1%) (P < 0.01).Cervical Pap smear test is necessary, safety and acceptable for routine prenatal tests. Any pregnant women with infections must be treated as nonpregnant one.