We investigated the fluorescence properties and the generation of nonphotochemical quenching at different intensities of illumination in the protist Euglena gracilis. Furthermore the influence of the carotenoid content on nonphotochemical quenching (qN) was tested. Depending on the light intensities used it is was possible to resolve the non-photochemical quenching into least three different components. The slowest phase of qN occurred only after exposure to high light and was assigned to photoinhibition. The two other components were identified by their different relaxation kinetics and sensitivity to inhibitors. In addition to an energy-dependent quenching (qE), whose dominated by carotenoid deficient cells of Euglena gracilis, another qN was observed which we attributed to a spill over mechanism. This processes was lost in carotenoid deficient cells. In contrast to higher plants, qE in Euglena gracilis is independent of a xanthophyll cycle and an aggregation of LHC II. Probably it is not localised in the antennae system.