Homoclinic motion plays a key role in the organization of classical chaos in Hamiltonian systems. In this Letter, we show that it also imprints a clear signature in the corresponding quantum spectra. By numerically studying the fluctuations of the widths of wavefunctions localized along periodic orbits we reveal the existence of an oscillatory behavior, that is explained solely in terms of the primary homoclinic motion. Furthermore, our results indicate that it survives the semiclassical limit. , an enhanced localization of quantum density along unstable short POs in certain individual eigenfunctions. This phenomenon was first noticed in the Bunimovich stadium billiard [3], and subsequently studied systematically by Heller, who constructed a theory of scarring based on wave packet propagation [4]. Another important contribution to scar theory is due to Bogomolny [5], who derived an explicit expression for the PO contributions to the smoothed quantum probability density over small ranges of space and energy (i.e. average over a large number of eigenfunctions). A corresponding theory for Wigner functions was developed by Berry [6]. Recently, there has been a flurry of activity focusing on the influence of bifurcations (mixed systems) on scarring [7].The existence of a scar implies a clear regularity in the corresponding quantum spectrum, related to the period of the PO. In time domain, the dynamics of a packet running along a PO induce recurrences in the autocorrelation function, that when Fourier transformed define an envelope in the spectrum, giving rise to peaks of width proportional to the Lyapunov exponent, λ, at energies given by a Bohr-Sommerfeld (BS) quantization condition [1,8].In this Letter, we demonstrate the existence of an additional superimposed spectral regularity also related to scarring. It is originated by the associated homoclinic motion and is given by the area enclosed by the stable and unstable manifolds up to the first crossing. To unveil this regularity we consider the fluctuations of the spectral widths corresponding to localized wavefunctions along unstable POs. Our data demonstrate that these fluctuations have a surprisingly simple oscillatory behavior essentially governed by the quantization of only the primary homoclinic dynamics. We provide an explanation of this result in terms of the coherence of this classical motion [9], which constitute the natural global extension of the local hyperbolic structure around the PO. Furthermore, our numerical results indicate that the observed oscillatory behavior do not vanish ash → 0.It should be remarked that, contrary to the previously described results on scar theory, our study implies dynamics beyond the Ehrenfest time (∼ | lnh|), when the PO manifolds start to cross and the homoclinic tangle develops, giving rise to subtle quantum interference effects. Other interesting papers, also considering these longer times, are due to Tomsovic and Heller [10], who showed how to construct a valid semiclassical approximation to wavefunctions past this l...