Abstract: The invention relates to topical ophthalmic preparations in eye drops containing bimatoprost as an active ingredient at the concentration of 0.1 mg/ml, wherein the presence of benzalkonium chloride is limited to the indispensable minimum commonly required for its activity as an antimicrobial preservative, i.e. from 50 at 80 ppm, and the bioavailability of the product is ensured by the addition of specific non-ionic surfactants, i.e., poloxamers.