The production of soft elastic gelatin capsules is a unique operation influenced by many factors. The fill and shell composition and conditions of drying are most important as they can reduce the liquid migration from the capsule wall into the fill and vice versa. Plasticizers improving elastic properties of soft gelatin capsules determine their hardness or softness as well as the dissolution rate of the shell. They play also an important role in liquid migration and thus have a great influence on capsule stability and bioavailability of the drug dissolved in the fill. The fill composition, plasticizers used in the capsule wall and their influence on the liquid migration and fill stability were studied.