© 2020 International Society for Horticultural Science. All rights reserved.An experiment was carried out in early-spring growing period under Mediterranean climatic conditions to investigate the effect of microalgae Chlorella vulgaris on nutrient saving of soilless grown greenhouse tomato. Eight treatments have been applied: 1) 100% full nutrition (control); 2) 100% full nutrition + algae; 3) 80% nutrition; 4) 80% nutrition + algae; 5) 60% nutrition; 6) 60% nutrition + algae; 7) 40% nutrition; 8) 40% nutrition + algae. Effects of Chlorella vulgaris on tomato plant growth, yield and fruit properties were investigated. Plant growth in the reduced nutrients were not decreased when the algae were added. The results showed the significant mineral nutrient saving in soilless application of Chlorella vulgaris. The higher total yields were obtained by 11.3 and 11.4 kg m-2 from 80% nutrition + algae and 60% nutrition + algae, respectively, when the control yield with 100% nutrition was 9.8 kg m-2. Yields in 80 and 60% nutrition with Chlorella vulgaris were increased by 15.4 and 21.7% compared to their own controls without algae. The algae had a significant increasing effect on average tomato fruit weight and fruit volume in 80 and 60% nutrition levels. The best effect of Chlorella vulgaris on the fruit quality has been to increase vitamin C content in the reduced nutrition levels. The algae can also increase some minerals content P, Na and Mg in tomato fruit. There was no significant effect of Chlorella vulgaris on pH at the root zone, but there was a significant lowering effect on EC.