Interlocking roof shingle has a front rounded tongue on the first side edge; a tongue on the first end edge; an elongated groove assembly on the upper surface with a groove defined therein; a groove in the second end edge of the body; a groove in the second side edge of the body; and an elongated tongue assembly on the lower surface. In an embodiment of the invention, the front rounded tongue of an upper roof shingle is inserted into the elongated groove assembly of a lower roof shingle while at the same time a leg of the elongated tongue assembly of the upper roof shingle enters into a groove in the second end edge of the lower roof shingle for interlocking upper and lower shingles. The tongue on the first end edge is inserted into a corresponding groove in the second end edge of an adjacent roof shingle.