The synthetic retinoids are a new class of drugs which are highly effective in the treatment of a broad spectrum of dermatologic disease. In this report 15 patients with chronic disorders of keratinization and one patient with severe cystic acne were treated with oral isotretinoin. The degree of clinical response and duration of post-treatment remission varied with the different disorders. Acute side effects were predominantly limited to the skin and mucous membranes and were reversible after discontinuation of treatment in these patients. Acute retinoid toxicity and the potential for developing chronic toxicity are reviewed. In an attempt to facilitate the monitoring of dermatologic patients treated with oral synthetic retinoids, we present our current guidelines for the use of these agents.