| All Vendors |
| Ocean Systems | Burtonsville, MD |
| Ocean Thin Films | Golden, CO |
| Olympus America, Inc. | Center Valley, PA |
| Omega Optical, Inc. | Brattleboro, VT |
| Orchid Cellmark | Dallas, TX |
| Orchid Pro-DNA, a division of Dynacare-Gamma Laboratory Partnership | Thunder Bay, Ontario, Canada |
| Original S.W.A.T. Footwear Co. | Modesto, CA |
| Overbrook Scientific, Inc. | Boston, MA |