Just and Arendshorst have hypothesized that the renal autoregulation (AR) response of RBF to step changes in BP involves a third component that is slower (time constant ~60–90 sec) than the tubuloglomerular feedback (TGF) and myogenic (MYO) mechanisms, and is independent of TGF. The goal of our study was to determine if such a very-low- frequency (VLF) component is evident in spontaneous and step change induced AR responses in RBF in anesthetized and conscious Sprague-Dawley rats and spontaneously hypertensive rats, as well as in cortical tissue (via a laser Doppler flow probe), and in single nephrons (via tubular pressure). High-resolution time-frequency representations (TFR) of renal flow data were obtained using the smoothed-pseudo Wigner-Ville method. From the TFR, a VLF band (~10 mHz) was often observed, as well as amplitude modulation of the power in the TGF and MYO bands (20–50 mHz and 100–300 mHz, respectively). To quantify this, power in these bands was tracked over time, and the resultant waveform was Fourier transformed. This revealed VLF amplitude modulation in both bands, with a peak centered at ~10 mHz, as well as a peak at TGF resonant frequency for the MYO band. In response to step changes in BP, power in the VLF band increased. After L-NAME, power in the VLF was evident, as was amplitude modulation of MYO oscillations at ~10 mHz. These VLF rhythms may reflect the operation of the third AR component, appears to modulate both TGF and MYO systems, and are consistent at all kidney levels. Funded by NIH HL69629