An object of the present invention is to providebetter formulations of a latanoprost ophthalmic solution.The present invention provides a clear ophthalmic solutioncomprising latanoprost as an active ingredient andbenzalkonium chloride as a preservative wherein whiteturbidity due to a change of formulation is prevented by atleast one means selected from the following 1) to 3)； 1)adding a surfactant, 2) using benzalkonium chloriderepresented by the formula of [C6H5CH2N(CH3)2R]Cl(wherein R is alkyl having 12 carbon atoms) as thepreservative and 3) adding a nonionic tonicity agent as atonicity agent.
