To assess the impact of chemoradiation on pelvic floor (PF) muscle function after the treatment of cervical cancer (CC). Methods We performed a prospective cohort study of women between the ages of 20 and 70 years old who had a diagnosis of CC. Patients were treated with chemoradiation at the Barretos Cancer Hospital (BCH), between August 2016 and July 2017. We performed three evaluations at different time points after chemoradiation treatment to compare changes in muscle function. Pelvic floor muscle function was assessed through perineometry (PNM) and surface electromyography (EMG) at the following time points: Pretreatment Moment 1 (M1): evaluated before chemoradiation; Moment 2 (M2): at the first follow-up medical visit (usually 3 to 4 months after treatment); and Moment 3 (M3): at the second follow-up medical visit (usually after 6 to 9 months after treatment). Mean vaginal squeeze pressure levels were determined by PNM and muscle electromyographic activity by EMG and the results were evaluated by Generalized Linear Model comparisons. Results Forty-nine patients were evaluated at M1; 35 at M2; and 32 at M3, so that 32 patients had all three muscle evaluations performed. There was a statistically significant increase in the frequency of women with urgency urinary incontinence at the M2 evaluation time (41.9%), compared to pretreatment M1 (18.6%), p<0.001. The means of the vaginal squeeze pressures reduced through M1 to M3 in the phasic (M1: 17.7 mmHg; M3: 11.27mmHg) and tonic contractions (M1: 10.56 mmHg; M3: 7.52mmHg), p = 0.01 and p = 0.03 respectively. There