Recently, the role of LHCs in photoprotection is into focus. In our study, we used wild type plants (control), Lhcb2-1 and Lhcb2-12 mutants having 20 % and 40 % reduction in LHC content. Two chlorophyll (Chl) fluorescence methods were used to investigate the response of photosystem II (PS II) to high light (HL 2000 micromol m-2 s-1). For an early respose, repetitive saturation pulses were applied in 10 s interval for 10 min and HL-induced change in effective quantum yield of PS II would be evaluated. The other approach was an analysis of fast Chl fluorescence kinetics (OJIPs) recorded before and after photoinhibitory treatment (30 min), and then after 60, 120, and 180 min of recovery under dim light. General response of quantum yield to a 10 min HL had a polyphasic character. It dropped immediately after HL initiation from 0.75 to almost zero. Then it exhibited curvilinear increase to a constat value (0.15) found at the end of HL treatment. After 30 min HL, OJIPs showed HL-induced decrease in Chl fluorescence values indicating strong photoinhibition of PS II. After 180 min recovery, Chl fluorescence increased towards pre-HL values indicating high capacity of photoprotective mechanisms. Simultaneously, content of antioxidants (zeaxanthin, glutathione) was evaluated in samples taken before and after 30, 60, 180, and 600 min recovery. The results showed that LHC-deficient A. thaliana mutants were more sensitive to photoinhibition than control. Supported by GACR52206097