To evaluate the nutritional values of Spirulina platensis as the protein supplement for laying heo diet, two experimental diets (Control, Spirulina platensis 2%) were prepared. Total 120, 40-wk old ISA Brown layer hens were randomly employed with 15 hens per replicate and 4 replicates per treatment. Hen-day egg production, egg weight, feed intake, intake /egg weight, egg shell thickness, yolk color score and yolk cholesterol content were examined during 6 weeks of experimental period. Hen-day egg production and feed conversion ratio (intake /egg weight) were significantly (P<0.01) improved by the 2% Spirulina plalensis supplementation. However, there were no differences in egg weight and feed intake between hens fed two experimental diets. Egg from hens fed Spirulina platensis 2% diet have more yellowish yolk color than the control egg although there was no difference in egg shell thickness. Yolk cholesterol content was significantly (P<o.01) decreased with Spirulina supplementation to the diet. The photosynthetic microalgae, Spirulina platensis was considered to he a favorable supplement for laying hen diet and the possibility to produce low cholesterol egg with Spirulina supplementation was recognized.