Isotretinoin (13-cis-retinoic acid) is commonly used for the treatment of acne vulgaris. In the skin this substance causes an atrophy of sebaceous gland acini and a decrease in sebum production. Systemic treatment also alters meibomian gland function and structure. These alterations seem to be responsible for ocular complications (dryness of the eye, blepharitis, conjunctivitis) during therapy with isotretinoin. We inspected 30 patients before, during and after therapy with isotretinoin with regard to ocular side effects. Examination included careful slit-lamp inspection, measurement of break-up time (BUT) and the Schirmer test. Conjunctival smears were taken from every patient. The most frequently observed side-effects were decreased tear break up time and alterations of the lid margin. In addition, an enormous increase of Staphylococcus aureus in conjunctival flora was noticed. However, all ocular complications of systemic treatment with isotretinoin were reversible after cessation of therapy.