AbstractGlidant and lubricant efficiencies of a number of different types of talcs were evaluated. Thein vitroproperties of tablets lubricated with talcs were compared to those lubricated with magnesium stearate. Talc lubricated tablets showed superiorin vitroproperties compared to magnesium stearate lubricated tablets. Different sources of talcs showed significant differences in glidant and lubricant efficiencies.