<p>Despite the growing importance of open and online higher education in widening access, student attrition remains a major concern. This study seeks to provide a large-scale descriptive analysis of student attrition in an Indonesian open university. Using administrative records from 1,547,096 student records between 2012 and 2025, the final analytical dataset included 1,546,888 students after data screening. Among them, 389,030 students were identified as attrited or non-active, representing approximately 25.15% of the final analytical sample. Descriptive statistics and chi-square tests were used to examine the distribution of attrited students across age, gender, working status, recognition of prior learning status and major. The findings show that attrited students were unevenly distributed across demographic and academic categories. Attrition cases were strongly concentrated among younger students, particularly those aged 20–24. Gender patterns became clearer when examined with working status: male attrited students were more concentrated among working students, whereas female attrited students were more concentrated among non-working students. A similar pattern was found for admission pathway, with non-RPL attrited students more concentrated among working students and RPL attrited students more concentrated among non-working students. Attrited students were also clustered in several majors, especially Primary School Teacher Education for In-Service Teachers, Management, and Law. This study contributes system-level evidence from an underrepresented Global South open higher education context. Importantly, the findings describe attrition concentration within the attrited population, not attrition risk relative to retained students. Therefore, the results should be interpreted as descriptive evidence to inform early-warning systems and subgroup-sensitive support.</p>