A few years ago, Nader Engheta and co-workers theoretically extended the circuit theory to the optical spectrum by arranging plasmonic and non-plasmonic elements into a nanostructure of total size much smaller than the used wavelength (N. Engheta, Science, vol. 317, p. 1698, 2007). The recipe was simple: Re(ε) > 0 for nanocapacitors, Re(ε) > 0 for nanoinductors, Im(ε) > 0 for nanoresistors, ε → 0 for insulators, and ε → ∞ for connectors. On the other hand, in RF and microwaves, it is well known that the duality between two complementary planar circuits allows for getting the electromagnetic behavior of one structure once its complementary is solved (H. G. Booker, J. Inst. Elect. Eng., vol. Pt. III-A, p. 620, 1946). This duality property is summarized by the formula: Z Z′ = η <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</inf> <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> /4, where Z and Z′ are the impedances of the original and complementary circuits, reciprocally, and ε <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</inf> is the vacuum impedance. However, this duality might not hold in the new framework of optical nanocircuits because metals are not longer good conductors but plasmonic materials. Therefore, duality would be limited just to RF and microwaves.