-syn region NITStmtBlock matchgroup=NITControl start="\<\(do\|then\|else\)\>\ze\s*\(#\|$\)" matchgroup=NITControl end="^\s*\<\(end\|\zeelse\|\ze!\)\>" contains=ALLBUT,NITTypeDecl,NITAttrDecl,NITInitDecl
-syn region NITStmtBlock matchgroup=NITControl start="\<\(do\|then\|else\)\>" matchgroup=NITControl end="\<end\>" oneline
+syn region NITStmtBlock matchgroup=NITControl start="\<\(do\|then\|else\|loop\)\>\ze\s*\(#\|$\)" matchgroup=NITControl end="^\s*\<\(end\|\zeelse\|\ze!\)\>" contains=ALLBUT,NITTypeDecl,NITAttrDecl,NITInitDecl
+syn region NITStmtBlock matchgroup=NITControl start="\<\(do\|then\|else\|loop\)\>" matchgroup=NITControl end="\<end\>" oneline