Abstract: The purpose of the study was to find out the effect of aerobic training with individualized heart rate based intensity on body mass index and cardio respiratory fitness among obese college men. For the purpose of the study 100 obese individuals, who were students of colleges were selected as subjects. They were treated as obese based on their BMI scores and divided in to two equal groups on BMI and cardio respiratory fitness scorers. All the subjects were assessed through PAR-Q (Physical Activity Readiness Questionnaire) before the selection. The experimental group underwent 12 weeks of aerobic training with individualized heart rate based intensity, four days in a week with a individualized target training zone of 60 % to of 70% their heart rate reserve for 45 minutes a day. The control group was not exposed to any experimental treatment. The training intensity was monitored through heart rate monitor. At the end of the 12 weeks both the experimental and control group were tested on their BMI and cardio respiratory fitness. Only the post test scores of the subjects on BMI and Cardio respiratory fitness were compared through‗t‘ ratio. It was concluded that the aerobic training with individualized heart rate based intensity showed a significant reduction in body mass index and significant improvement on cardio respiratory fitness among obese College men.