Gamma ray-induced polymerization of butyl acrylate (BA) and acrylonitrile (AN) was carried out at room temperature in a microemulsion with high monomer content stabilized by a mixture of sodium of 12-acryloxy-9-octadecenoic acid (AOA) and sodium dodecyl sulfate (SDS) at a weight ratio of 4. Special Y-shaped structure of AOA promotes the efficiency of monomer solubilization and gamma ray radiation contributes to the stability of microemulsion during the polymerization process. Microlatexes were characterized by dynamic light scattering (DLS) and scanning electron microscopy (SEM). Results showed that microlatex particles with a narrow size distribution were obtained. The effects of monomer composition, dose rate, monomer concentration, and surfactant concentration on the microlatexes are discussed.