This chapter includes a discussion of antifungal, antimalarial, and antiviral drugs. Similarities and differences of these with antibacterial antibiotics are discussed. Drugs presented include amphotericin B, nystatin, azoles, allylamines, morpholines, fluoropyrimidines, DDT, quinine, chloroquine, pyrimethamine, artemisinin, proguanil, amantadine, acyclovir, lamivudine, zidovudine, and HIV protease and neuraminidase inhibitors. Mechanisms of action of the drugs and resistance development against them are discussed. PCR method for detection of point mutations is also discussed.