Siderophores are iron--chelating agents synthesized by microbes to overcome low availability of iron in the growth environment. In some pathogenic bacteria like Bacillus anthracis, they act as virulence mediators and the strains incapable producing siderophores are non-pathogenic. In the current study, the efficiency of siderophore production in Bacillus anthracis and Serratia marcescens was estimated in different growth conditions. The growth in terms of protein was found to be greater in S. marcescens than B anthracis at all growth conditions. Siderophores detected in Chrome Azurol Assay and the estimated production of hydroxamate type and catechol type siderophores were greater in S marcescens in comparison to B. anthracis. The studies revealed a greater efficiency of siderophore production in S marcescens than B anthracis irrespective of the growth conditions.