Ultraviolet-A (UV-A) radiation induced changes in photosystem II (PS II) of senescing leaves of wheat seedlings were investigated. UV-A radiation did not show any significant effect on the level of photosynthetic pigments. However, the decline in F_v / F_m and oxygen evolution rate indicated the damaging effect of the radiation on primary photochemistry of PS II. Modification at the Q_B-binding site was B inferred from the observed downshift of peak temperature of hermoluminescence (TL) B-bands. The UV-A induced changes in PS II of chloroplasts from senescing leaves were found to be synergistically  accelerated by high growth temperature.