Provided is a glass cloth enabling to reduce a mass of the glass cloth, being manufactured efficiently, suppressing generation of pinholes in a prepreg including the glass cloth, and maintaining excellent appearance. The glass cloth is composed of warps and wefts obtained by bundling 30 to 44 glass filaments having a diameter in the range of 3.0 to 4.0 m, the weave densities of the warp and the weft being in the range of 100 to 125 yarns/25 mm; the glass cloth has a thickness in the range of 6.5 to 11.0 m; the glass yarn coverage C is 85.5 to 99.5%; and the glass yarn coverage C, the average value F of the number of glass filaments constituting the warp and the weft, and the average value D of the weave densities of the warp and the weft satisfy the following expression (1):
53.0CF.sup.1/2/D.sup.1/257.3(1).

Provided is a glass cloth enabling to reduce a mass of the glass cloth, being manufactured efficiently, suppressing generation of pinholes in a prepreg including the glass cloth, and maintaining excellent appearance. The glass cloth is composed of warps and wefts obtained by bundling 30 to 44 glass filaments having a diameter in the range of 3.0 to 4.0 m, the weave densities of the warp and the weft being in the range of 100 to 125 yarns/25 mm; the glass cloth has a thickness in the range of 6.5 to 11.0 m; the glass yarn coverage C is 85.5 to 99.5%; and the glass yarn coverage C, the average value F of the number of glass filaments constituting the warp and the weft, and the average value D of the weave densities of the warp and the weft satisfy the following expression (1):

53.0CF.sup.1/2/D.sup.1/257.3 (1).

A printed circuit board (PCB) composite material includes a polymer layer and a fiber layer encapsulated within the polymer layer. The fiber layer includes a first monolayer of continuous silica fibers longitudinally co-aligned in a first direction. Each continuous silica fiber in the first monolayer extends without discontinuity through the polymer layer such that opposed ends of each continuous silica fiber are adjacent to a perimeter of the polymer layer. The PCB composite material has a dielectric loss tangent of less than or equal to about 0.0015 at 15 GHz or higher frequency. A printed circuit board (PCB) includes the PCB composite material and at least one conductive layer disposed on a side of the PCB composite material.