The effects of two green microalgal strains, Chlorella oocystoides and Chlorella minutissima, on some growth parameters of Zea mays and on some soil physico-chemical properties were studied. The growth mass, chlorophyll content, phosphorous content, and potassium content of maize plants were significantly increased. The increase of other parameters such as plant length, number of leaves, and total nitrogen was not statistically significant. Concerning the studied soil physicochemical properties, the soil total nitrogen significantly increased by inoculation with algal strains. Also the soil organic matter significantly increased with all the used concentrations of the two algae. The pH significantly decreased with 1%, 2.5%, and 5% of C. oocystoides, while there was no significant change with the second alga.