We present a noise reduction filter for the phase unwrapping of data from phase-shifting speckle pattern interferometry. This filter is effective in reducing the noise in wrapped phase maps without affecting the edges of the phase jumps, so that a simple and fast unwrapping algorithm can be used. We also discuss a data analysis strategy, including a routine for the recovery of unwrapping errors. The filter performance has been evaluated on real data from a fiber optic phase-shifting speckle interferometer, which we built for the analysis of out-of-plane deformations. The phase shifting is introduced by current modulation of the diode laser source. Some results relative to the analysis of very noisy phase measurements are presented. © 1997 Society of Photo-Optical Instrumentation Engineers.