The effect and arrangement of cytoskeleton (microtubules, microfilaments and neurofilaments) in neurulation of chick embryo examined by immunoperoxidase method from stage 6 to stage 12. The results were as follows: 1) Microtubules aggregated in the perinuclear region from which they radiated to take longitudinal course beneath the membrane. 2) Microfilaments were aggregated in the apical ends (free-surface) of neural epithelium causing the cells to become flask-shaped. 3) Neurofilaments (Nfs) had no important role in neural tube formation