Tubular pressure oscillations in pairs of cortical nephrons derived from a common cortical radial artery are often synchronized. To determine the extent and duration of synchronization among many nephrons on the renal surface of rats we used laser speckle microscopy. The camera measures the intensity of speckle pattern fluctuations associated with blood flow variations. Time series were sampled from the speckle image at star vessels whose locations were identified on the renal surface by ordinary digital microscopy during intravenous dye injection and then were overlaid on the time averaged speckle image. The time series analyzed with wavelet transform show oscillations associated with both tubuloglomerular feedback (TGF) and the myogenic mechanism. Synchronization in the form of TGF frequency entrainment is present among groups of nephrons but persists for variable periods of time. The size of synchronization clusters also varies with time. In this way, the laser speckle flowmetry combined with wavelet analysis can provide new insight into global behavior of nephrons in a vascularly coupled ensemble.