Cathepsin S inhibitors

Disclosed are compounds of formulae (I) and (II), wherein the substituents are as defined in the specification, compositions comprising the compounds and processes for their preparation. The compounds are selective, reversible inhibitors of cathepsin S and are therefore useful in the treatment of autoimmune and other diseases, including rheumatoid arthritis, systemic lupus erythematosus, Crohn's disease, ulcerative colitis, multiple sclerosis, Guillain-Barre syndrome, psoriasis, Grave's disease, myasthenia gravis, scleroderma, glomerulonephritis, dermatitis including contact and atopic dermatitis, insulin-dependent diabetes mellitus, endometriosis, asthma, Alzheimer's disease and atherosclerosis.