There are conceptual and historical links between homeopathic medicine and modern allergy desensitization treatment. Conventional allergy desensitization and homeopathic treatment both utilize small doses of substances that might cause symptoms in order to prevent or treat a hypersensitive state. Homeopathy has historically been associated with allergy treatment. This article reviews evidence from controlled trials for the use of homeopathy in respiratory allergies. Several clinical trials, many of which were published in "high impact" conventional medical journals, describe significant effects of homeopathic treatment in allergic patients. Most of these clinical studies have been deemed to be high quality trials, according to the three most commonly referenced meta-analyses of homeopathic research. Basic in vitro experimental studies also provide evidence that the effects of homeopathy differ from placebo.