This study evaluated the physicochemical and sensory characteristics of cookies containing various concentrations(0, 3, 5, 7 and 9%) of Enteromorpha intenstinalis powder. Cookies containing E. intenstinalis powder were significantly lower in L value than of the control. The L value of brightness decreased significantly when E. intenstinalis powder was added to the cookie formula. The a and b values also decreased significantly with the addition of E. intenstinalis powder. The loss and leavening rates were significantly higher when 5% E. intenstinalis powder was added to the samples. The spread ratio increased proportionally with the amount of E. intenstinalis powder added to the cookie formulation The hardness decreased significantly according to the amount of E. intenstinalis powder. A sensory evaluation of acceptability(appearance, flavor, color, texture and overall quality) indicated that adding a 5% E. intenstinalis powder was most the acceptable treatment compared to the other treatments.