Background We have retrospectively assessed the incidence and outcome of women diagnosed during a hospital-based cytology screening program with "atypical squamous cells (ASC)" and followed-up with loop electrical excision procedure (LEEP). Methods We analyzed 173,947 cases of cervical smears' follow-up cytology and histology findings. Previous or archival cytology with LEEP results were retrieved for 390 women with ASC of undetermined significance (ASC-US) and 112 with ASC, cannot exclude high-grade squamous intraepithelial lesion (ASC-H). Results On the follow-up cytology, of the 390 women initially diagnosed with ASC-US, 130 (33.3%) had no follow-up records of smears before LEEP; smears of 18 (4.6%) were negative for cytologic abnormalities, 193 (49.5%) were ASC-US, 24 (6.2%) were ASC-H, 111 (28.5%) were low grade squamous intraepithelial lesion (SIL), and 44 (11.4%) were high grade SIL. LEEP findings in these 390 women showed that 183 (46.9%) were negative, 73 (18.7%) were graded as cervical intraepithelial neoplasia (CIN) 1, 25 (6.4%) as CIN 2, 102 (26.2%) as CIN 3, and 7 (1.8%) had carcinoma. LEEP was performed in 112 women initially diagnosed with ASC-H; 36 (32.1%) were negative, 4 (3.6%) were graded as CIN 1, 7 (6.3%) as CIN 2, 60 (53.6%) as CIN 3, and 5 (4.5%) with carcinoma. Conclusions Patients with ASC-H smears were at increased risk of SIL or carcnoma compared with patients with ASC-US. Careful follow-up is required in ASC patients.