The present application describes novel spiro-cyclic -amino acid derivatives of formula I: ##STR1##

or pharmaceutically acceptable salt forms thereof, wherein ring B is a 3-13 membered carbocycle or heterocycle, ring C forms a 3-11 membered spiro-carbocycle or spiro-heterocycleon ring B, and the other variables are defined in the present specification, which are useful as as matrix metalloproteinases (MMP), TNF- converting enzyme (TACE), and/or aggrecanase inhibitors.