Infectious skin conditions of the adult patient that primary care providers may often encounter in practice include those of viral (herpes simplex, herpes zoster, verruca and condylomata, molluscum), fungal (candidiasis, dermatophyte infections) and ectoparasitic (scables, pediculosis) origin. Correct diagnosis and treatment of these conditions can provide relief to the patient and prevent spread to household and sexual contacts. This article discusses the epidemiology, etiology, history, appearance, diagnosis, and treatment of these commonly encountered infectious skin conditions. The primary care provider can differentiate these skin conditions by history, appearance, and laboratory tests, and should be able to diagnose and provide cost-effective therapy and secondary prevention for them. The primary care provider should also be able to recognize those lesions that are harbingers of systemic diseases and appropriately refer for further management.