The K-12 Basic Education Curriculum of the Philippines need to be constantly monitored for the least mastered content (LMC). The LMC is one of the basis of the Department of Education (DepEd) in improving the current curriculum. This study utilized survey method using e-assessment to identify the LMC in Grades 3 to 10 and its causes. The results of the identified LMC is an indication that unattained knowledge and skills continuously recur in the latter part of education of the learners. It is apparent that the learning contents in four areas of Science (Earth Science, Biology, Chemistry, and Physics) have expected higher attrition as grade level increases. With the identified LMC among the grade levels, the Education Program Supervisors recommended for content training and workshops for teachers, provision of instructional materials for specific topics, team-teaching between a non-specialized teacher and a teacher expert and assessment training and workshops for teachers. The utilization of e-assessment enhances and hastens the identification of the LMC which promotes efficiency and immediate action of the DepEd.