Microbial contamination in cultures of the alga,Scenedesmus acutus raised in outdoor open tanks and also in the processed powder of the alga was monitored; The total bacterial population increased with time during the growth period of six days. When a combination of molasses and carbondioxide was employed as carbon source for this alga, the bacterial load increased to 10 colony forming units/ml. Yeast, molds and also coliforms were quantitated. Drum-drying the algae drastically reduced the bacterial load and storing the algal powder for a period of over 3 months did not increase the bacterial load. Pathogens likeSalmonella andStaphylococcus were not detectable either in the open cultures or in the drumdried algal powder. Although there are not set standards available in literature on the permissible level of the microbial contamination in algal biomass for use in foods, the microbial load appears to be within the limits of permissible levels stipulated by Indian Standard Institution standards for baby foods.