Equilibrium moisture content (EMC) data have been obtained for two representative tablet granulations. These data are useful in analysis of drying operations and particularly in predicting final moisture contents obtainable in "dried" products. The effects of drying variables, such as relative humidity and inlet air temperature, on product moisture levels are established. Similarly, the influence of storage conditions on moisture gain is predictable. Data obtained from drying studies -with a lactose placebo granulation are used to illustrate the relationship between equilibrium moisture content values and minimum required drying times. The importance and economic advantages obtainable by review of this type data before establishment of moisture specifications for dried materials is illustrated. In addition, equilibrium moisture content values for several tablet fillers, disintegrants, and other pharmaceuticals are presented. Based on these preliminary studies, the EMC concept may have useful applications in the design of moisture stable products.