The molecular structure of melanins has been a focus of study for many years and only recently has a molecular model (MM) been proposed based upon x‐ray scattering results. In order to test the validity of the model, scanning tunneling microscopy (STM) and spectroscopy have been performed on the same tyrosine‐derived melanin, which has been characterized in the x‐ray scattering studies and has been shown to exhibit characteristics of natural melanins. The STM measurements of the lateral and vertical dimensions provide a characteristic fundamental size which agree well with the x‐ray scattering‐derived MM. We find that the compact three‐dimensional structure is best described as a planar morphology of finite lateral extent (≊2 nm) with a vertical extent (<1 nm) which is believed to consist of stacks of a basic two‐dimensional amorphous polymer of 5,6 indolequinone units. Molecular mechanics and orbital calculations of representative amorphous models support the x‐ray scattering and STM results.