Particle Image Velocimetry (PIV) has seen a rapid growth over the last two decades, much owing to the developments in digital cameras and solid state laser technologies. PIV can essentially be looked upon as an application of pattern mathching principles to experiments. We rely upon hardware such as lasers and cameras for illumination and image capture. Subsequently we use computer code to perform the pattern matching. MatPIV is one of a variety of different computer coedes available written specifically for this purpose. The vast majority of codes are commercially available, but in the last 7-8 years several Open Source PIV codes have been created and are currently being more or less actively maintained. MatPIV is one of these codes and it is distributed under the GNU General Public License [MatPIV is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. The GNU General Public License can be found on the World Wide Web at http://www.gnu.org/copyleft/gpl.html or it can be obtained by writing to the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.] This document acts as the entry level tutorial fr using the MatPIV code. Very basic theory is reviewed and references to appropiate sources are included. The focus, however, is on the use of MatPIV and how it is implemented.