Abstract: The light scattering phenomena in PbM₀O₄ single crystal are studied.It is suggested that clusters of point defects (clusters of vacancies) and the microscopic non-uniform field caused by interaction between vacancies and dislocations be the main cause of light scattering. The number and distribution of vacancies and dislocations as well as their mechanism of motion are studied. A method of eradicating light scattering centes is presented.