The purpose of this study was to investigate the effects of punch speed and lubrication (with and without the addition of 1% magnesium stearate) on the compaction properties of some commonly used commercial direct compression agents. The compressibility of these materials was analyzed using compression parameters derived from the Heckel equation. Three different classes of excipients having plastic, elastic and brittle fragmentation characteristics were evaluated, including microcrystalline cellulose (Avicel PH 101), pregelatinized starch (Starch 1500) and dibasic calcium phosphate (Fujicalin). Tablets were prepared using a compaction simulator under 20 kN force with a flat-faced 11mm punch. Three different speeds were investigated 10, 50 and 100 mm/sec. Data demonstrated that plastic materials like Avicel PH 101 form harder tablets at low compression speeds whereas brittle fragmenting materials like Fujicalin were relatively unaffected by compaction speed. Avicel PH 101 gave the hardest tablets at all compression speeds with and without the addition of lubricant