Participation in physical activities and sports has been identified as a factor, that influence self-esteem positively. However, other studies have shown that exercise only increased self-esteem with respect to body image. Many studies have focused on the effect of a particular exercise routine on self-esteem rather than physical activity in general. This study focused on identifying the effect of volume of physical activities on self-esteem among undergraduates of a private University in Colombo. A descriptive cross sectional study was designed with a sample size of 61 undergraduates recruited through snowball sampling. The self-administered International Physical Activity Questionnaire (Short form), Rosenberg selfesteem scale and demographic data questionnaire along with an information sheet, consent form and debrief form was sent online to undergraduates of a private University in Colombo. The mean age of the sample was 21.62 (2.2). The majority of the sample were minimally active (62.3%) and the mean volume of total energy expenditure was 1356 MET min/week which is below the HEPA category. The majority of the sample had a high level of self-esteem (82%). A binary logistic regression analysis was carried out to examine the impact of BMI, total time spent in sitting and total volume of energy spent, on the level of self-esteem. The model accounted for only 18.3%-30.0% of variance in outcome. However, only total volume of energy spent showed a significant impact on predicting the level of self-esteem (Wald= 5.20, p<0.05). The odds of having a high self-esteem decreased with the total volume of energy spent. The undergraduates had a relatively good physical activity level and self-esteem. However, with the increase of volume of physical activity, self-esteem decreased significantly. Further research should be carried out to confirm the effect of body-esteem , body dissatisfaction, type of exercise, frequency of exercise, gender or other variables to decipher this relationship.