diff --git a/pyrogram/methods/messages/send_invoice.py b/pyrogram/methods/messages/send_invoice.py
index 0dde16d9..ce72bdcf 100644
--- a/pyrogram/methods/messages/send_invoice.py
+++ b/pyrogram/methods/messages/send_invoice.py
@@ -39,6 +39,7 @@ class SendInvoice:
         message_thread_id: int = None,
         quote_text: str = None,
         quote_entities: List["types.MessageEntity"] = None,
+        reply_markup: "types.InlineKeyboardMarkup" = None
     ):
         """Use this method to send invoices.
 
@@ -96,6 +97,9 @@ class SendInvoice:
                 List of special entities that appear in quote_text, which can be specified instead of *parse_mode*.
                 for reply_to_message only.
 
+            reply_markup (:obj:`~pyrogram.types.InlineKeyboardMarkup`, *optional*):
+                An inline keyboard. If empty, one 'Buy' button will be shown.
+
         Returns:
             :obj:`~pyrogram.types.Message`: On success, the sent message is returned.
 
@@ -112,6 +116,21 @@ class SendInvoice:
                 ))
         """
 
+        if reply_markup is not None:
+            has_buy_button = False
+            for i in reply_markup.inline_keyboard:
+                for j in i:
+                    if isinstance(j, types.InlineKeyboardButtonBuy):
+                        has_buy_button = True
+            if not has_buy_button:
+                text = "Pay"
+                if currency == "XTR":
+                    prices_total = 0
+                    for price in prices:
+                        prices_total += price.amount
+                    text = f"Pay ⭐️{prices_total}"
+                reply_markup.inline_keyboard.insert(0, [types.InlineKeyboardButtonBuy(text=text)])
+
         reply_to = await utils.get_reply_to(
             client=self,
             chat_id=chat_id,
@@ -145,7 +164,8 @@ class SendInvoice:
                 ),
                 random_id=self.rnd_id(),
                 reply_to=reply_to,
-                message=""
+                message="",
+                reply_markup=await reply_markup.write(self) if reply_markup is not None else None
             )
         )
 
diff --git a/pyrogram/types/bots_and_keyboards/inline_keyboard_button_buy.py b/pyrogram/types/bots_and_keyboards/inline_keyboard_button_buy.py
index 3f74f2a1..1ac3effe 100644
--- a/pyrogram/types/bots_and_keyboards/inline_keyboard_button_buy.py
+++ b/pyrogram/types/bots_and_keyboards/inline_keyboard_button_buy.py
@@ -15,9 +15,12 @@
 #
 #  You should have received a copy of the GNU Lesser General Public License
 #  along with Pyrofork.  If not, see <http://www.gnu.org/licenses/>.
+import pyrogram
 
 from ..object import Object
 
+from pyrogram import raw
+
 class InlineKeyboardButtonBuy(Object):
     """One button of the inline keyboard.
     For simple invoice buttons.
@@ -42,4 +45,7 @@ class InlineKeyboardButtonBuy(Object):
             text=b.text
         )
 
-    # TODO: Implement write method
+    async def write(self, _: "pyrogram.Client"):
+        return raw.types.KeyboardButtonBuy(
+            text=self.text
+        )
diff --git a/pyrogram/types/bots_and_keyboards/inline_keyboard_markup.py b/pyrogram/types/bots_and_keyboards/inline_keyboard_markup.py
index e91d1e0d..7ddcb69e 100644
--- a/pyrogram/types/bots_and_keyboards/inline_keyboard_markup.py
+++ b/pyrogram/types/bots_and_keyboards/inline_keyboard_markup.py
@@ -29,8 +29,10 @@ class InlineKeyboardMarkup(Object):
     """An inline keyboard that appears right next to the message it belongs to.
 
     Parameters:
-        inline_keyboard (List of List of :obj:`~pyrogram.types.InlineKeyboardButton`):
+        inline_keyboard (List of List of :obj:`~pyrogram.types.InlineKeyboardButton` | :obj:`~pyrogram.types.InlineKeyboardButtonBuy`):
             List of button rows, each represented by a List of InlineKeyboardButton objects.
+            :obj:`~pyrogram.types.InlineKeyboardButtonBuy` objects is only for :meth:`~pyrogram.Client.send_invoice`.
+            and only one needed in the first row.
     """
 
     def __init__(self, inline_keyboard: List[List[Union["types.InlineKeyboardButton", "types.InlineKeyboardButtonBuy"]]]):