Within the recent years novel lead optimisations for histamine H(3) receptor antagonists made their way from bench to bedside. Structure-activity relationships, cross-affinities and side effects as well as pharmacokinetic profiling will be discussed on selected promising compound series. Due to diversity in potential therapeutic applications and in some cases a controversial debate, different indications will be highlighted with the potential and the problems of the test compounds, e.g. sleep-wake disorders, attention-deficient hyperactivity disorder, epilepsy, cognitive impairment, schizophrenia, obesity and neuropathic pain. First data published on clinical trials phase II (IIb) are presented showing proof of concept of H(3) receptor antagonists in narcolepsy and photo-induced epilepsy.