Doxycycline is clinically effective in the treatment of variety of infections such as: Rickettsial infections including ehrlichiosis, typhus, spotted fever, trench fever and Q fever; chlamydial infections including psittacosis, lymphogranuloma venereum, trachoma, non-gonococcal urethritis; mycoplasmal infections especially pneumonia; Legionnaires' disease; gonorrhea and syphilis; and surgical infections prophylaxis. Prophylaxis of leptospirosis.