AbstractHuman embryos aged six and one‐half through 1 weeks were studied to determine the morphological changes in shape of the maxillary dental arch during this early developmental period. Age was determined by crown‐rump lengths using the table of Patten ('53).When compared to a reference catenary curve, the embryonic dental arch exhibited several time‐linked and directional changes in shape. First, 6.5 to 8 week embryos characteristically had upper dental arches which were wide and anteroposteriorly flattened and did not conform to the catenary curve. At 7.5 to 9 weeks, the C‐shaped dental arch showed more elongation and increasing depth. It was not until weeks 9.5 to 12 that the embryonic dental arch grew enough to conform to the catenary curve.It is suggested that the catenary curvature of the postnatal upper dental arch can be first recognized as early as 9.5 weeks of deve