The final concentrations of non-axenic outdoor mass cultures of Dunaliella sp. grown for two or three days in f/2 and 2f media were found to be dependent on the initial cell concentration, since the cultures started with 80 × 10³ cells ml^-1 gave better yields than those started with 40 × 10³ cells ml^-1. There was a correlation between nutrient availability and cell yields: the two and three days-old cultures started with 40 × 10³ cells ml^-1 and grown in medium f/2 had lower concentrations than those grown in 2f medium, whereas in cultures with 80 × 10³ cells ml^-1 inoculum the yield was significantly higher only after three days. The lowest dry biomass yields after two and three days were with the inoculum of 40 × 10³ cells ml^-1 and medium f/2.