A case of multiple lesions of junctional melanocytic hyperplasia arising in a skin graft after excision of a congenital melanocytic naevus is reported. This observation is shown to support the concept of the histogenesis of acquired melanocytic naevi proposed by Cramer [2], i.e. that acquired melanocytic naevi are derived from melanocyte precursors located in nerve sheaths, whereas it is inconsistent with notions of the origin of naevogenesis in the epidermal melanocyte.