Effects of light and temperature on the nitrate uptake and germling growth of Enteromorpha compressa (L.) Greville (Chlorophyta) were studied based on samples from Cheongsapo near Busan, Korea. In addition, their effects on fatty acids composition in thallus were examined. Nitrate uptake showed saturation kinetics. $V_{max}$ (maximal uptake rate) and its $K_s$ (half-saturation constant) at $20^{circ}C,;80;{mu}mol;m^{-2}s^{-1},$ white light were $1.571;{mu}mol{cdot}g;fr;wt^{-1}{cdot}h^{-1}$ and 3.56 ${mu}M$, respectively. In nitrate uptake with irradiance, wavelength and temperature, its rate represented respectively the highest value as $1.405pm0.020,;0.623pm0.040,;1.422pm0.022;{mu}mol{cdot}g;fr;wt^{-1}{cdot}h^{-1};at;100;{mu}mol;m^{-2}s^{-1},$ red light, $20^{circ}C$ and exhibited significant difference among the examined conditions (p<0.001). Germling growth of E. compressa also showed saturation kinetics, and $V_{max}$ and its $K_s$ value at $20^{circ}C,;100;{mu}mol;m^{-2}s^{-1},$ 12:12 h were $56.18\%;day^{-1}$ and 0.33 ${mu}M$, respectively. SGR (specific growth rate) recorded a maximal value as 49.33-54.80, 39.07-50.72, $47.20-54.53\%;dat^{-1}$ at $120;{mu}mol;m^{-2}s^{-1},$ blue light and $18^{circ}C$ respectively, and showed significant difference (p<0.001). Red light made the effective nitrate uptake, but germling growth was largely limited by the light. In fatty acids analysis, PUFAs (polyunsaturated fatty acids) were high at blue light, $18^{circ}C,;100;{mu}M;NO_3^-.$ However, irradiance did not affect the production of PUFAs. In conclusion, nitrate uptake and germling growth of E. compressa showed saturation kinetics to external nitrate concentration, and were significantly affected by irradiance, wave length and temperature. Fatty acid composition was also influenced by the factors except for irradiance. Their maximal values, together with the highest production of PUFAs, were found at blue light band, $20^{circ}C,;100;{mu}mol;m^{-2}s^{-1},;and;100;{mu}M;NO_3^-.$