Brodimoprim, is a new 2,4-diaminobenzylpyrimidine that , that selectively inhibits bacterial and resistance plasmid dihydrofolate reductases to a similar or greater extent than trimethoprim. Brodimoprim is two to three times more potent than trimethoprim and has more than 100-fold the affinity for dihydrofolate reductase with analogous enzymatic activity of eukaryotic cells. Brodimoprim’s in vitro activity is similar to that of trimethoprim. Brodimoprim is decidedly superior to trimethoprim in vivo in the mouse acute infection model, due to its much longer elimination half-life and better tissue diffusion. Acute and subacute toxicity tests in traditional laboratory animals show that there is little difference between brodimoprim and trimethoprim. Brodimoprim had no teratogenic or embryotoxic effects and mutagenic analysis was negative