Objectives. To assess the frequency and factors associated with parametrial involvement (PI) in patients with cervical cancer IB1 who underwent radical hysterectomy (RH) at the National Institute of Neoplastic Diseases in Peru. Materials and methods. Cross-sectional study of 214 patients with cervical cancer IB1 undergoing RH with pelvic lymphadenectomy between 2007 and 2012. The population was compared with and without clinicopathological variables associated with PI such as age, tumor size, depth of infiltration, histological grade and pelvic lymph node involvement. Results. Ten patients (4.6%) had PI. Multivariate analysis showed that the depth of invasion (OR 8.37, 95% CI 1.24-56.41, p=0.029) and pelvic node involvement (OR 18.03; 95% CI 3.30-98.44, p=0.001) were all independent predictors of PI. The presence of tumor size ≤ 2 cm, invasion ≤ 10 mm, absence of lymphovascular permeation and absence of nodal involvement identified 97 patients at low risk of PI, none of whom had PI pathology. Conclusions. We confirmed the low frequency of PI in the cervical cancer IB1 subgroup and its association with the depth of invasion and lymph node involvement suggested in previous studies. This information will allow the identification of a subgroup of patients at low risk of PI for less radical surgery in our institution.