The present invention relates to a sunscreen formulation which exhibits superior ultraviolet protection and water resistance than prior art sunscreen compositions. The sunscreen formulation comprises (a) a dispersion comprising a sunscreen active agent and (b) a base composition comprising a rheological modifying agent and water. The sunscreen formulation is substantially free of surfactants. According to a preferred embodiment, the sunscreen active agent is ethylhexylmethoxycinnamate, butylmethoxydibenzoylmethane, or a combination thereof. The sunscreen formulation preferably comprises a phosphorylated starch derivative as a rheological modifying agent. Another embodiment of the present invention is a method of protecting skin or hair from ultraviolet radiation by applying an effective amount of the sunscreen formulation of the present invention to the skin or hair.