The dispersion of vinyl chloride monomer (VCM) in aqueous solutions of polyvinyl alcohol (PVA) stabilisers has been studied experimentally. A 11 pressurised vessel was used together with a newly designed external pressurised optical cell. The validity of assuming local isotropy in the experiments was confirmed. Parameters affecting the initial VCM dispersion, such as stirring time, turbulence intensity and type and concentration of suspending agent have been studied in derail and the results compared with existing theories. The Sauter mean diameter (D-32) is proportional to N--1.2, confirming the predominance of the drop breakage mechanism. The transitional time for a dynamic equilibrium to be established in the dispersions was found to be 30 min. When the degree of hydrolysis of the PVA increases, the drop size increases and the VCM drops become more stable towards coalescence. With one of the PVAs (H72) the critical PVA concentration, for a constant drop size, was found to be equal to 0.012%.