Seventy-four ovocytes were obtained by puncturing 188 follicles. Several criteria were tasted for their applicability to accurate assessment of ovocyte maturity or possible degenerative changes. They were diameters of follicles and ovocytes, number of rows and structure of granulous cells and of the pellucid zone, contours, granulation, and optical properties of cytoplasm, and existence of a germinal vesicle. Only seven of the above 74 ovocytes were mature and normal in structure. Proposed is a method for isolation of ovocytes by sedimentation of follicular fluid.