diff --git a/src/ast/statements.hpp b/src/ast/statements.hpp
index 01c5914..1197760 100644
--- a/src/ast/statements.hpp
+++ b/src/ast/statements.hpp
@@ -190,4 +190,26 @@ struct Module : Node
         }
         return oss.str();
     }
+};
+
+struct While : Stmt
+{
+    ptr<Expr> condition;
+    std::vector<ptr<Stmt>> body;
+
+    While(ptr<Expr> cond, std::vector<ptr<Stmt>> b)
+        : condition(std::move(cond)), body(std::move(b)) {}
+
+    std::string dump(int indent = 0) const override
+    {
+        std::ostringstream oss;
+        oss << indent_str(indent) << "While\n";
+        oss << condition->dump(indent + 1);
+        for (const auto &stmt : body)
+        {
+            oss << "\n"
+                << stmt->dump(indent + 1);
+        }
+        return oss.str();
+    }
 };
\ No newline at end of file
diff --git a/src/lexer.l b/src/lexer.l
index 21f0bd3..1aa4919 100644
--- a/src/lexer.l
+++ b/src/lexer.l
@@ -49,6 +49,7 @@ pass                    { return yy::parser::token::TOK_KW_PASS; }
 else                    { return yy::parser::token::TOK_KW_ELSE; }
 elif                    { return yy::parser::token::TOK_KW_ELIF; }
 class                   { return yy::parser::token::TOK_KW_CLASS; }
+while                   { return yy::parser::token::TOK_KW_WHILE; }
 
 \=\=                    { return yy::parser::token::TOK_EQ; }
 \!\=                    { return yy::parser::token::TOK_NE; }
diff --git a/src/parser.y b/src/parser.y
index a7a72cb..df091f1 100644
--- a/src/parser.y
+++ b/src/parser.y
@@ -32,7 +32,7 @@
 %left KW_OR
 %left KW_AND
 %right KW_NOT          // unary logical NOT
-%token KW_DEF KW_IF KW_RETURN KW_FOR KW_IN KW_PASS KW_ELSE KW_ELIF KW_CLASS
+%token KW_DEF KW_IF KW_RETURN KW_FOR KW_IN KW_PASS KW_ELSE KW_ELIF KW_CLASS KW_WHILE
 
 %token L_PAREN R_PAREN L_BRACKET R_BRACKET L_BRACE R_BRACE
 %token DOT COLON SEMICOLON COMMA
@@ -94,6 +94,9 @@ stmt:
     | KW_RETURN expr NEWLINE { 
         $$ = std::make_unique<Return>(std::move($2));
     }
+    | KW_WHILE expr COLON NEWLINE INDENT stmt_list DEDENT {
+        $$ = std::make_unique<While>(std::move($2), std::move($6));
+    }
     ;
 
 expr:
@@ -102,6 +105,7 @@ expr:
     | STRING              { $$ = std::make_unique<String>($1); }
     | expr PLUS expr      { $$ = std::make_unique<BinOp>( BinaryOperator(BinaryOperator::ADD), std::move($1), std::move($3)); }
     | expr MULTIPLY expr  { $$ = std::make_unique<BinOp>( BinaryOperator(BinaryOperator::MUL), std::move($1), std::move($3)); }
+    | expr MINUS expr     { $$ = std::make_unique<BinOp>( BinaryOperator(BinaryOperator::SUB), std::move($1), std::move($3)); }
     | expr LT expr        { $$ = std::make_unique<BinOp>( BinaryOperator(BinaryOperator::LT) , std::move($1), std::move($3)); }
     | expr KW_AND expr    { $$ = std::make_unique<BinOp>( BinaryOperator(BinaryOperator::AND) , std::move($1), std::move($3)); }
     | expr KW_OR expr     { $$ = std::make_unique<BinOp>( BinaryOperator(BinaryOperator::OR) , std::move($1), std::move($3)); }
diff --git a/test/parser/25.in b/test/parser/25.in
index f505c42..f9afc99 100644
--- a/test/parser/25.in
+++ b/test/parser/25.in
@@ -1,3 +1,2 @@
 while x:
-    x = x - 1
-
+    x = x - 1
\ No newline at end of file
diff --git a/test/parser/25.out b/test/parser/25.out
index bfa717f..51a2439 100644
--- a/test/parser/25.out
+++ b/test/parser/25.out
@@ -5,5 +5,4 @@ Module
       Identifier(x)
       BinOp(-)
         Identifier(x)
-        Number(1)
-
+        Number(1)
\ No newline at end of file