The development of the nanocrystalline silicon inclusions in homogeneous and multilayered a-Si:H films was investigated by transmission electron microscopy (TEM). The homogeneous a-Si:H films were obtained by continuous deposition at constant gas mixture (CGM) mode and the multilayered films were obtained by the layer by layer (LBL) method, i.e. using intermediate annealing in hydrogen plasma. Initial CGM and LBL films were completely homogeneous and amorphous. After annealing at 450 °C approximately the same volume fraction (1–2%) and size (10 nm) of nc-Si inclusions was observed in both CGM and LBL films. However, after annealing at 750 °C CGM films became polycrystalline with a grain size of about 1 μm, while LBL films were nanocrystalline with nc-Si average size of 10 nm, which did not exceed the layer thickness deposited per cycle. This effect gives a new way of controlling the size and amount of nanocrystalline inclusions in a-Si:H films.