diff --git a/erpnext/buying/doctype/purchase_order/purchase_order.js b/erpnext/buying/doctype/purchase_order/purchase_order.js
index c0fc95c..ba215c1 100644
--- a/erpnext/buying/doctype/purchase_order/purchase_order.js
+++ b/erpnext/buying/doctype/purchase_order/purchase_order.js
@@ -56,6 +56,8 @@
 					 this.delivered_by_supplier).addClass("btn-primary");
 			}
 		} else if(doc.docstatus===0) {
+			cur_frm.add_custom_button(__('Get Last Purchase Rate'), this.get_last_purchase_rate);
+			
 			cur_frm.cscript.add_from_mappers();
 		}
 
@@ -204,6 +206,16 @@
 
 	delivered_by_supplier: function(){
 		cur_frm.cscript.update_status('Deliver', 'Delivered')
+	},
+	
+	get_last_purchase_rate: function() {
+		frappe.call({
+			"method": "get_last_purchase_rate",
+			"doc": cur_frm.doc,
+			callback: function(r, rt) {
+				cur_frm.cscript.calculate_taxes_and_totals();
+			}
+		})
 	}
 
 });
diff --git a/erpnext/buying/doctype/purchase_order/purchase_order.py b/erpnext/buying/doctype/purchase_order/purchase_order.py
index 2a6ab88..f68935f 100644
--- a/erpnext/buying/doctype/purchase_order/purchase_order.py
+++ b/erpnext/buying/doctype/purchase_order/purchase_order.py
@@ -8,6 +8,7 @@
 from frappe import msgprint, _, throw
 from frappe.model.mapper import get_mapped_doc
 from erpnext.controllers.buying_controller import BuyingController
+from erpnext.stock.doctype.item.item import get_last_purchase_details
 from erpnext.stock.stock_balance import update_bin_qty, get_ordered_qty
 from frappe.desk.notifications import clear_doctype_notifications
 
@@ -83,6 +84,34 @@
 			if d.prevdoc_detail_docname and not d.schedule_date:
 				d.schedule_date = frappe.db.get_value("Material Request Item",
 						d.prevdoc_detail_docname, "schedule_date")
+						
+
+	def get_last_purchase_rate(self):
+		"""get last purchase rates for all items"""
+		
+		conversion_rate = flt(self.get('conversion_rate')) or 1.0
+
+		for d in self.get("items"):
+			if d.item_code:
+				last_purchase_details = get_last_purchase_details(d.item_code, self.name)
+
+				if last_purchase_details:
+					d.base_price_list_rate = (last_purchase_details['base_price_list_rate'] * 
+						(flt(d.conversion_factor) or 1.0))
+					d.discount_percentage = last_purchase_details['discount_percentage']
+					d.base_rate = last_purchase_details['base_rate'] * (flt(d.conversion_factor) or 1.0)
+					d.price_list_rate = d.base_price_list_rate / conversion_rate
+					d.rate = d.base_rate / conversion_rate
+				else:
+					# if no last purchase found, reset all values to 0
+					for field in ("base_price_list_rate", "base_rate", 
+						"price_list_rate", "rate", "discount_percentage"):
+							d.set(field, 0)
+
+					item_last_purchase_rate = frappe.db.get_value("Item", d.item_code, "last_purchase_rate")
+					if item_last_purchase_rate:
+						d.base_price_list_rate = d.base_rate = d.price_list_rate \
+							= d.rate = item_last_purchase_rate
 
 	# Check for Stopped status
 	def check_for_stopped_or_closed_status(self, pc_obj):