Substituted 2-(2,6-dioxopiperidin-3-yl)phthalimides and 1-oxo-2-(2,6-dioxopiperidin-3-yl)isoindolines reduce the levels of TNFα in a mammal. Typical embodiments are 1-oxo-2-(2,6-dioxo-3-methylpiperidin-3-yl)-4,5,6,7-tetrafluoroisoindoline and 1,3-dioxo-2-(2,6-dioxo-3-methylpiperidin-3-yl)-4-aminoisoindoline.