Abstract： Objective To investigate the value and safety of biopsy guided by colposcopy in diagnosis of cervical diseases in pregnant women.Methods From Aug.2007 to Feb.2009.17 828 pregnant women who receive antenatal examination underwent cervical cytological screening thinprep cytology test(TCT)in Beijing Obstetrics and Gynecology Hospital.If abnormal cytological results were found,those preguant women were administered by eolposcopic examination and biopsy after they signed informed consent.Results (1)TCT:the abnormal TCT results of 1502 preguant women(8.425%,1502/17 828) were found in 17 828 cases.(2)Colposeopie examination:two hundred and four pregnant women underwent colposcopic examination.The rate of satisfied colposcopic imaging wag 92.6%(189/204),colposcopic examination identified 125 cages with cervical inflammation or cervical intraepithelial neoplasia (CIN)Ⅰ,25 cases with CIN Ⅱ and 54 cases with CIN Ⅲ or microinvasive squamous carcinoma (MIVC) of squamous cervical carcinoma(SCC).(3)The results of biopsy guided by colposcopy:among 204 cases,it was found 33 cases with cervical inflammation or wart,95 cases with CIN Ⅰ,28 CIN Ⅱ,36 cases with CIN Ⅲ and 12 cases with MIVC. (4) The rate of concordance: compared with biopsy pathologic examination, colposcopy examination found 113 cases with cervical inflammation and CIN Ⅰ , the rate of concordance was 90. 4%(113/125). And 54 cases with CIN Ⅲ or SCC diagnosed by colposcopy examination, however biopsy pathologic examination confirm 23 cases with CIN % and 10 cases with SCC at stage Ⅰ a, the concordance rate was 61% (33/54). (5) Complication: eight (3.9%, 8/204) pregnant women underwent cervical wound suturing due to continuous bleeding after colposcopy exam or biopsy. No other complications were recorded. Conclusions It is necessary that TCT should be performed in pregnant women without cytological screening within one year. Colposcopic examination and biopsy were indicated if pregnant woman with abnormal cytological result were found. Pregnant women with cervicitis or CIN Ⅰ diagnosed by colposcopy should be followed up. If pregnant woman was suspected with CIN Ⅱ or advanced disease, biopsy guided by colposcopy should be performed.