The present invention provides C.sub.1-6alkyl-4-amino-azepan-3-one protease inhibitors and pharmaceutically acceptable salts, hydrates and solvates thereof which inhibit proteases, including cathepsin K, pharmaceutical compositions of such compounds, novel intermediates of such compounds, and methods for treating diseases of excessive bone loss or cartilage or matrix degradation, including osteoporosis; gingival disease including gingivitis and periodontitis; arthritis, more specifically, osteoarthritis and rheumatoid arthritis; Paget's disease; hypercalcemia of malignancy; and metabolic bone disease; and parasitic diseases, including malaria, by administering to a patient in need thereof one or more compounds of the present invention.