Pharmacological inhibition of capsule opacification e.g. using antimitotics such as daunomycin is a promising concept. Our own in vitro studies on cultured porcine lens epithelial cells have shown, that daunomycin penetrates the cells within at least 5 minutes. It possesses a low acute cytotoxicity and significantly inhibits epithelial cell proliferation at dose dependent concentrations ranging from 2.5 to 7.5 mg/l. In addition, in vitro studies on isolated pig corneas showed almost no corneal endothelial toxicity. After 10 resp. 30 min. exposure to 7.5 mg/l daunomycin, there was only 4.8 +/- 1.6 resp. 6.1 +/- 1.5% endothelial damage that dit not significantly differ from BSS serving as control. Encouraged by our clinical experience of good anterior segment tolerance of 7.5 mg/l daunomycin when used during vitrectomy in PVR, we started a prospective clinical trial to assess the effect to daunomycin on capsular opacification after ECCE with endo-capsular IOL implantation using the envelope technique. After agreement of the medical ethic commission we chose 6 patients with a mean age of 78 (72-83), no other ocular or general diseases and bilateral cataract of identical morphology and density. After written consent of the patients their first eye was operated using BSS as control. At least 4 weeks later the second eye was operated and received 0.5 ml of daunomycin (7.5 mg/l) applied during 5 minutes into the cleaned capsular bag, leaving the anterior capsular flap and a Healon filled anterior chamber to protect the surrounding intraocular structures. Mean postoperative control time actually is 12 (6-17) months for the controls and 10 (5-14) months for the eyes treated with daunomycin.(ABSTRACT TRUNCATED AT 250 WORDS)