Objective: The objective of this study was to evaluate the level of physical activity and its association with hemoglobin level among undergraduate students. Method and materials: A cross-sectional study was conducted on undergraduate students of Isra Institute Rehabilitation Sciences, Isra University Islamabad. The undergraduate students between 18- 25 years were included in the study. The hemoglobin level was evaluated through the hemoglobin-meter and physical activity through the International Physical Activity Questionnaires IPAQ-SF-7. The Pearson product-moment correlation was used to find association between physical activity and hemoglobin level. Results: The mean age of study participants was 21.10±1.76. Of the 400 participants, 22% participants had low level of physical activity, 46.25% participants had moderate level of physical activity and 31.75% participants had vigorous physical activity. The time spent in vigorous and moderate physical activity was significantly associated with the hemoglobin level (p<0.05) and sitting was negatively correlated with Hb (p<0.05). Conclusion: It was concluded that that levels of physical activity was significantly associated with the hemoglobin level. Keywords: Physical activity, hemoglobin, anemia.