Respiratory viruses lead to exacerbations of chronic respiratory diseases such as chronic obstructive pulmonary disease and asthma. Many risk factors play a role in the development of asthma and COPD. The homocysteine is thought to play a role in the pathogenesis of asthma and COPD. In this research we aimed to determine homocysteine levels in individuals with asthma and COPD presenting adenovirus and respiratory syncytial virus infections in a period of exacerbated respiratory disease to predict the risk factors that could lead to the development of cardiovascular diseases. Viral agents were determined using ELISA methods. Measurement of homocysteine level was performed with high-performance liquid chromatography. According to the results, the rate of RSV was 41.9% (36/86) and the rate of adenovirus was 34.9% (30/86) in patients with asthma, while the rate of RSV was 40.5% (30/74) and the rate of adenovirus was 39.2% (29/74) in patients with COPD disease. While the homocysteine levels ranged from 10.39 to 16.66 μmol/l in the control group, homocysteine levels of asthma patients were found to be between 13.12-25.21 μmol/l, and in COPD patients, these were found between 12.96-25.96 μmol/l. The homocysteine levels in COPD patient were found statistically significantly higher than control group data (p<0.05). The determination of the homocysteine levels and viral respiratory agents in patients with asthma or COPD reduce the risk of mortality and morbidity and help to predict the risk factors that could lead to development of cardiovascular diseases.