This study examined the influence of lemon drink intake during exercise on the autonomic nervous system activity. Four test drinks (500g each) of lemon water, lemon fruit water, honey lemon water, and honey lemon fruit water were prepared. The lemon water and lemon fruit water were prepared by the addition of lemon juice (40g) and lemon fruit powder (1g) to water, respectively. The honey lemon water and honey lemon fruit water were prepared by the addition of honey (4g) to the above lemon drinks. Six healthy male subjects (average age, 21.3 years) exercised using an exercise bike for 20 min at the heart rate from 110 to 120 bpm. They freely ingested all the test drink during the exercise. The autonomic nervous system activity was examined by measuring the variation in the fingertip heart rate before exercise, after exercise, and after a 30-min. rest. For the intake of the honey lemon water, the LF/HF level (sympathetic nerve activity) after exercise was shown to significantly increase in comparison to that before exercise ( p <0.05). For the intake of the lemon fruit water, the HF level (parasympathetic nerve activity) after rest was shown to have a tendency to significantly increase in comparison to that before and after exercise ( p <0.1). Based on these results, it was suggested that the intake of the honey lemon water during exercise increased the sympathetic nerve activity after exercise and that of the lemon fruit water has a tendency to increase the parasympathetic nerve activity after exercise rest.