Etretinate and its metabolite acitretin have been shown to be highly effective in the treatment of various disorders of keratinization, including lamellar ichthyosis. The aim of the present study was to provide further information on acitretin dosage regimens in the management of lamellar ichthyosis. Seven patients with classical manifestations of lamellar ichthyosis participated in the study. Five patients improved markedly, and the remaining patients showed mild to moderate improvement. Two patients improved following gradual incremental increase in dosage (> or = 35 mg/day). Four patients, including a patient with the erythrodermic variant, required low-dose acitretin treatment (< or = 25 mg/day), as higher doses resulted in a marked deterioration in their skin condition. The dichotomy with respect to the response to acitretin suggests that lamellar ichthyosis is a spectrum of at least two conditions.