Gelatin zymography is a widely used technique to study matrix metalloproteinases (MMP)-2 and −9, characterized by its simplicity, low cost, and high sensitivity. Zymography can detect picogram quantities of MMPs, which is 100–1000-fold more sensitive than immunoblot. The shortcoming of a traditional zymography protocol is the absence of an in-gel loading control to detect and correct any errors in sample loading. Here we describe a simple method that combines gelatin zymography with an in-gel glyceraldehyde-3-phosphate dehydrogenase (GAPDH) immunoblot loading control, thus combining sensitivity and accuracy in a single assay.