In this paper, the purification, crystallization and preliminary X-ray crystallographic studies of human carnitine acetyltransferase are reported. Recombinant human carnitine acetyltransferase crystals were grown by the hanging-drop vapor-diffusion method and belong to the orthorhombic space group P2(1)2(1)2(1), with unit-cell parameters a = 137.65, b = 84.76, c = 57.65 A and one molecule per asymmetric unit. The intensity data were collected from a cryocooled crystal to 1.6 A resolution using a conventional X-ray source.