Doped ZnS nanocrystals have attracted attention since 1994. Previous results suggest that doped semiconductor nanocrystals form a new class of luminescent materials, which have a wide range of applications in displays, lighting, sensors and lasers. In this work we synthesized Y3+ doped ZnS nanoparticles by a chemical precipitation method. The reaction was performed with ZnSO4, Na2S, phosphates and Yttrium acetate in aqueous solution. Fluorescence (FL) studies of these nanoparticles have been carried out. FL analysis reveals that the incorporation of Yttrium and phosphates to colloidal solution of ZnS nanoparticles enhances the FL signal by 6-7 times of magnitude compared with uncapped ZnS nanoparticles.