Preoperative serum squamous cell carcinoma antigen (SCC) levels were examined in 148 cases of stage Ib squamous cervical cancer undergoing radical hysterectomy. The effect of the pelvic lymph node status on the marker level was examined by comparing 113 cases with cancer limited to the uterus and 23 cases with cancer confined to the uterus and pelvic lymph nodes using two different multivariate analyses. Ninety-five percent of patients with cancer limited to the uterus showed SCC levels of 4 ng/ml or below. Nearly two-thirds (65%) of patients with serum levels above 4 ng/ml exhibited pelvic lymph node metastasis. The marker values exceeding 4 ng/ml increased the risk of nodal metastasis by eight times, compared with serum levels of 4 ng/ml or below. Multivariate analyses confirmed that the pelvic lymph node metastasis had a larger impact on the marker level than did tumor size or depth of stromal infiltration. SCC levels greater than 4 ng/ml can be considered a high-risk zone for nodal metastasis.