ScreenUrSelf aims to verify whether the offer of urine or vaginal self-sampling is more effective than an invitation letter to contact a physician for a Pap smear or no intervention, to generate participation in cervical screening without negatively impacting compliance to follow-up. Would home-collected urine sampling be more preferred by un(der)-screened women than vaginal self-sampling? Could as such more women be reached that currently do not participate in organized screening? To define which intervention is most effective to reach un(der)-screened women, a trial will be embedded in the organized cervical screening program in Flanders (Belgium). 48000 women (30-64y) will be included, who are eligible for screening but were not screened for at least six years (two screening rounds). Women will be randomized in six arms each comprising 8000 women: two control (no intervention; recall letter) and four intervention arms. Interventions consist of receipt of a urine or vaginal self-sampling kit (opt-out) or receipt of a letter to order a urine or vaginal self-sampling kit (opt-in). The primary outcome will be the response rate: proportion of women that participate in each study arm within twelve months after initiation of the intervention. Response is defined as having a preventive cervical screen, by the self-sample or a Pap smear. Secondary study outcomes will include percentage of screened positive women with follow-up, percentage of women with a positive screen test, positive predictive value of a positive screen test, detection rate of high-grade cervical neoplasia, preference and attitudes of women, age- and socioeconomic status-related differences in response rates, and cost-effectiveness outcomes. Offering a cost-effective approach that reaches un(der)-screened women and assures compliance to follow-up should impact significantly on the burden of cervical cancer. If embedded in an organized screening program, this could positively impact both the patient’s health and reduce costs for the healthcare system.