A miniature laser-Doppler velocimeter (LDV) system was developed to make simultaneous three-velocity-component measurements. The probe has been tested in a zero-pressure gradient two-dimensional turbulent boundary layer and the results agree well with earlier data and several DNS data sets. The overall size of the probe is 23.3 mm × 8.7 mm × 90.6 mm and measurement spatial resolution is 50 µm. The probe volume can be traversed 32 mm vertically. The lightweight and compact design of the LDV probe head allows the probe head to be embedded inside models and machinery for three-dimensional turbulent flow measurements where larger probes are unusable.