The objective was to evaluate the prevalence and factors affecting residual disease in women with cervical microinvasive carcinoma (MIC) with positive cone margins for high-grade lesions and invasive carcinoma. We reviewed histopathology slides of 129 women with MIC who had high-grade lesions or invasive carcinoma at cone margins. These patients underwent hysterectomy following cone biopsy between January 1994 and June 2004. Of the 129 patients, 77 (59.7%) had residual disease in the hysterectomy specimens, in which 57 (44.2%) had residual high-grade lesions. Twenty patients (15.5%) had residual invasive carcinoma: 18 were microinvasive and 2 were invasive. Factors significantly affecting the risk of residual disease included positive postconization endocervical curettage (P= 0.001), positive cone margins for invasive carcinoma (P= 0.003), and depth of stromal invasion >1 mm (P= 0.014). Cox proportional hazards analysis revealed positive cone margins for invasive carcinoma as significant predictor of residual invasive disease (hazard ratio, 3.22; 95% CI 1.21-8.60, P= 0.019) In summary, patients with MIC and positive cone margins for high-grade lesions or invasive carcinoma are at high risk of residual neoplasia. Repeat cone biopsy should be performed to determine exactly the severity of lesion before planning treatment.