This invention provides novel compounds, and pharmaceutically acceptable derivatives thereof, that are useful as caspase inhibitors. These compounds have the general formula I: ##STR00001## where R.sup.1, R.sup.2, and R.sup.3 are as described herein, Ring A contains zero to two double bonds, each X is independently selected from nitrogen or carbon, at least one X in Ring A is a nitrogen, Ring A is optionally substituted as described, and may be fused to a saturated or unsaturated five to seven membered ring containing zero to three heteroatoms, and provided that when X.sub.3 is a carbon, a substituent on X.sub.3 is attached by an atom other than nitrogen.