The aim of this study is to explore problems in radiotherapy for breast cancer patients in Yogyakarta, Indonesia, focusing on overall treatment time (OTT) and completion rate. A retrospective cohort study was conducted based on data from the Insurance Unit at a tertiary hospital in Yogyakarta, Indonesia. The study included all female outpatients with breast cancer who were treated with radiotherapy from January to December 2017 and met the inclusion criteria. The primary outcomes were OTT and completion rate. The secondary outcomes included the number of radiotherapy fractions, radiotherapy doses, number of radiotherapy interruption days, and reasons for radiotherapy interruption. The chi-squared and Mann-Whitney U tests were used to assess the differences in outcomes between two insurance schemes (JKN-PBI (Beneficiaries of Health Insurance Contribution Assistance) and JKN-NON-PBI (Non-Beneficiaries of Health Insurance Contribution Assistance)). The sample included 285 breast cancer patients (mean age: 53 years). The median OTT was 38 days (IQR: 17-48 days), with 123 (43.2%) patients having prolonged OTT. The completion rate was 57.9%. No significant differences in OTT (44.4% vs. 35.7%, p= 0.445) and completion rate (57.2% vs. 61.9%, p= 0.569) were found between the JKN-NON-PBI and JKN-PBI groups, respectively. In all, the data reported 3,022 interrupted days of radiotherapy across a total of 227 patients. The most common reason for radiotherapy interruption was unknown. There are problems in timely delivery and low completion rate of radiotherapy among breast cancer patients in Indonesia. There are no significant differences in OTT and completion rate between the insurance schemes.