The study aims to determine the metacognitive awareness and academic achievement in genetics among the eleventh standard students through the Problem Based Learning (PBL) approach. The Sample for the study (n=106) were selected in three schools in Chennai through purposive cluster sampling technique. Single group pre-post test comparison design was used to collect the data using the Metacognitive awareness Inventory (MAI) and achievement test in genetics constructed by the researcher. Appropriate statistical analysis of the collected data reveal that PBL was more effective in developing metacognitive awareness among the students and enhanced the students to reveal their academic potential in learning genetics.