The purpose of this Comment is first to correct the claim of Smolyaninov and Hung [Phys. Rev. B 75, 033411 (2007)] that the reported results "strongly contradict" the presence of diffracted evanescent waves in the vicinity of subwavelength structures and second to point out that periodic structures are unnecessary for the efficient production of the surface plasmon polariton guided mode either as traveling or standing waves. Guided surface waves originate from simple slit or groove edges illuminated under normal incidence, and one-dimensional surface cavities from these standing waves are easily realized.