An oily formulation of fulvestrant or derivatives thereof and a method forproducing the same.The oily formulation comprises: fulvestrant or derivatives thereof in anamount of 10 mg/ml to170 mg/ml; a lactate compound in an amount of 5 to 80% of the total weight ofthe formulation;a vegetable oil or synthetic oil (ester); an analgesic; and an optionalantioxidant.