Cedar pollen allergies are one of the severe health problems in Japan. Recently, it was reported that symptoms of pollen allergies are attenuated by the intake of functional foods. Euglena is a unicellular organism classified as algae, which is taking notice as a functional food. In this study, the effect of euglena on experimental pollen allergies in mice was investigated.   5 week-old BALB/c male mice were sensitized using Cry j1 by intraperitoneal injection and intranasal instillation. AIN-93M was fed to the negative control and positive control group, whereas euglena, paramylon, and amorphous paramylon were fed (2% in AIN-93M) to each diet group. We determined the incidence of nasal rubbing, liver weight, spleen weight, white blood cell counts, serum IgE and IFN-γ.   In the euglena diet group, the percentage of positive incidences of nasal rubbing mice decreased. It is suggested that euglena may attenuate symptoms of cedar pollen allergies.