The Harlech Grits Group is a lower to middle Cambrian lithostratigraphic group (a sequence of rock strata) in northwest Wales.

The name is derived from the town of Harlech in Gwynedd.

The rocks are exposed beneath Harlech and across the Harlech Dome to its east; a broad anticlinal structure which encompasses the Rhinogydd range.

[1] The group comprises about 2000m thickness of sandstone, mudstones, siltstones and greywackes laid down in the marine Welsh Basin during the early to mid Cambrian period.

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