Congenital ichthyosis is a collective name for a group of monogenetic disorders of cornification, sometimes associated with systemic symptoms. There may be an abnormal quality or quantity of scale produced, abnormal thickness of stratum corneum or abnormal keratinocyte kinetics, often associated with skin inflammation. Pruritus, skin fragility, ectropion and anhidrosis are sometimes associated with the rare types of ichthyosis. Three important mechanisms are involved in the action of topical agents used in the treatment of ichthyosis: hydration, lubrication and keratolysis. The latter effect can also be achieved with systemic retinoids. For ichthyosis with an increased tendency towards skin infections, antimicrobials are another group of widely used agents. Considering that patients with ichthyosis are potential mega-users of topical therapy, with an estimated lifetime consumption of approximately one tonne cream per capita, surprisingly few controlled trials of the various treatments have been performed. Moreover, nearly all therapeutic principles were established long before the recent increase in knowledge about the aetiology and pathophysiology of ichthyosis. This calls for new ideas and intensified efforts to develop future ichthyosis therapies.