The present invention relates to peptidyl phosphonate esters compounds and their use selective inhibitors of proteinase 3, in particular for treating or diagnosing inflammator autoimmune and cancer disorders. More specifically, the invention concerns nov peptidyl phosphonate esters compounds, including without limitation, compounds with Asp-Tyr-Asp-Ala or Pro-Tyr-Asp-Ala, Pro-Tyr-Asp-Avl, Val-Tyr-Asp-Avl peptide structure or their derivatives.