Wheat seedlings were exposed to He-Ne laser irradiation (5 mW·mm-2 power density),enhanced ultraviolet-B (UV-B) radiation (10.08 kJ·m-2·d-1),and the combination of He-Ne laser irradiation and enhanced UV-B radiation for 5 days. Changes of DNase activity and RNase activity in the leaves and roots of wheat seadlings were measured to test the potential reparative role of He-Ne laser irradiation. The results show that exposing the seedlings to UV-B radiation results in the increase of the nuclease activity of the leaves and roots. The electrophoresis pattern of nuclease shows that enzyme spectrum zones do not increase,whereas enzyme activity increases. After irradiating by UV-B and the He-Ne laser,the nuclease activity of the leaves and roots becomes is lower than their activity under UV-B radiation alone. The electrophoresis pattern of nuclease also shows that enzyme spectrum zones do not decrease,whereas enzyme activity decreases. The results suggest that damage,induced by enhanced UV-B radiation on wheat seedlings,which affects the activity of nuclease in leaves and roots,can be repaired partially by He-Ne laser irradiation.