Spores of four Frankia-Casuarina strains were tested for their ability to infect and fix atmospheric nitrogen in combination with Casuarina equisetifolia plants, after being stored for 3 and 6 months in different media. The media used were liquid cultures (BAP) and wet or dry polyacrylamide. The Frankia strains used were: UGL020601, UGL020604, HFPCcI3 and ORS021001. Inoculation with stored spore inocula showed reduction in total nitrogen content. The reduction ranged between 33 and 88% of freshly prepared spores-inoculated plants, depending on strain and the inoculum type. The wet gel-incorporated Frankia strains scored the best values within all treatments. In general, the reduction in plant total nitrogen was lower after 3 months than after 6 months of storage at 7°C for all treatments indicating better performance after short storage. The number of nodules decreased gradually with the increase in storage time for all strains and treatments. For all the tested strains, spores scored better values for root/shoot and nodules/plant ratios (i.e. lower and higher ratios) for all strains stored for 3 months, as wet gel, than for other treatments. Dry powdered gel may have an advantage of long "shelf- life" than the other treatments and may be used also as a preservation medium for large-scale inoculation with Frankia. In general, it is recommended to store dry or wet gel-immobilized Frankia spores in the refrigerator for up to 3 months for commercial purposes.