Poly(methy methacrylate) latex with various solid contents, stabilized electrostatically, was studied. The hydrodynamic layer (H.L.) extends rapidly at volume fraction larger than 0.35. The agglomeration of particles was found. When the reduced thickness (delta/r) of H.L. exceeds 3.0, particle agglomeration becomes more serious and the gel-like product forms. In comparison, the value of (delta/r) is much smaller than 3.0 when the H.L. begins to contact each other. Using a higher amount of emulsifier, the thickness of H.L. decreases. This is attributed to the fact that more free emulsifier presenting in the aqueous phase leads to more depletion stabilization. Meanwhile, in the presence of unreacted monomer, the use of the monomer-swollen volume fraction is suggested to replace the unswollen volume fraction.