Background: Diaphragmatic breathing, also known as deep breathing, involves the diaphragm to enhance oxygen exchange and has shown various physiological benefits. This study aims to investigate the effect of diaphragmatic breathing on serum hemoglobin levels in healthy vegetarian adults. Understanding this relationship could provide insights into non-pharmacological interventions for improving respiratory efficiency and blood oxygenation.  Methods: This randomized controlled trial included 100 healthy vegetarian adults aged 20- 50 years from Anand City, Gujarat, India. Participants were randomly assigned to either the intervention group (n=50), which performed diaphragmatic breathing exercises, or the control group (n=50), which did not receive any specific breathing exercises. The intervention consisted of daily 30-minute sessions, 5 days a week, for 8 weeks. Serum hemoglobin levels were measured at baseline and post-intervention. Statistical analysis was performed using paired t-tests to compare pre and post-intervention hemoglobin levels within each group and independent t-tests to compare changes between groups. A p-value of less than 0.05 was considered significant. Results: The intervention group showed a significant increase in serum hemoglobin levels from 13.8 ± 1.2 g/dL to 14.4 ± 1.1 g/dL (p=0.03), while the control group showed no significant change (13.7 ± 1.3 g/dL to 13.6 ± 1.2 g/dL, p=0.67). The change in hemoglobin levels was significantly greater in the intervention group compared to the control group (p=0.03). Conclusion: Diaphragmatic breathing exercises significantly increased serum hemoglobin levels in healthy vegetarian adults. This non-invasive intervention could be a potential strategy for enhancing respiratory function and overall health. Further research is warranted to explore the underlying mechanisms and long-term benefits.