The molecular morphology of long G4-DNA wires made by a novel synthetic method was, for the first time, characterized by high-resolution scanning tunneling microscopy (STM). The STM images reveal a periodic structure seen as repeating "bulbs" along the molecules. These bulbs reflect the helix morphology of the wires. The STM measurements were supported by a statistical morphology analysis of the DNA pitch length and apparent height relative to the surface. In the absence of X-ray and NMR data for these wires, the STM measurements provide a unique alternative to characterize the helix morphology.