diff --git a/ClosedXML/Excel/CalcEngine/CalcEngine.cs b/ClosedXML/Excel/CalcEngine/CalcEngine.cs
index 1738b2f..0b0aa20 100644
--- a/ClosedXML/Excel/CalcEngine/CalcEngine.cs
+++ b/ClosedXML/Excel/CalcEngine/CalcEngine.cs
@@ -444,10 +444,11 @@
                 // sub-expressions
                 case TKTYPE.GROUP:
 
-                    // anything other than opening parenthesis is illegal here
+                    // Normally anything other than opening parenthesis is illegal here
+                    // but Excel allows omitted parameters so return empty value expression.
                     if (_token.ID != TKID.OPEN)
                     {
-                        Throw("Expression expected.");
+                        return new EmptyValueExpression();
                     }
 
                     // get expression
diff --git a/ClosedXML/Excel/CalcEngine/Expression.cs b/ClosedXML/Excel/CalcEngine/Expression.cs
index 286bedd..01399b9 100644
--- a/ClosedXML/Excel/CalcEngine/Expression.cs
+++ b/ClosedXML/Excel/CalcEngine/Expression.cs
@@ -403,6 +403,15 @@
             return (_value as IEnumerable).GetEnumerator();
         }
     }
+
+    /// <summary>
+    /// Expression that represents an omitted parameter.
+    /// </summary>
+    class EmptyValueExpression : Expression
+    {
+        internal EmptyValueExpression() { }
+    }
+
     /// <summary>
     /// Interface supported by external objects that have to return a value
     /// other than themselves (e.g. a cell range object should return the
diff --git a/ClosedXML/Excel/CalcEngine/Functions/Logical.cs b/ClosedXML/Excel/CalcEngine/Functions/Logical.cs
index 18d2a9d..581e97a 100644
--- a/ClosedXML/Excel/CalcEngine/Functions/Logical.cs
+++ b/ClosedXML/Excel/CalcEngine/Functions/Logical.cs
@@ -47,7 +47,14 @@
             {
                 return p[1].Evaluate();
             }
-            return p.Count > 2 ? p[2].Evaluate() : false;
+            else if (p.Count > 2)
+            {
+                if (p[2] is EmptyValueExpression)
+                    return false;
+                else
+                    return p[2].Evaluate();
+            }
+            else return false;
         }
 
         static object True(List<Expression> p)
@@ -72,4 +79,4 @@
             }
         }
     }
-}
\ No newline at end of file
+}
diff --git a/ClosedXML_Tests/Excel/CalcEngine/FunctionsTests.cs b/ClosedXML_Tests/Excel/CalcEngine/FunctionsTests.cs
index 48691a6..af57751 100644
--- a/ClosedXML_Tests/Excel/CalcEngine/FunctionsTests.cs
+++ b/ClosedXML_Tests/Excel/CalcEngine/FunctionsTests.cs
@@ -616,5 +616,25 @@
             Assert.AreEqual(0, cell.Value);
             Assert.That(() => wb.Worksheet(1).Cell(3, 1).SetFormulaA1("=AVERAGE(D1,D2)").Value, Throws.Exception);
         }
+
+        [Test]
+        public void TestOmittedParameters()
+        {
+            using (var wb = new XLWorkbook())
+            {
+                object value;
+                value = wb.Evaluate("=IF(TRUE,1)");
+                Assert.AreEqual(1, value);
+
+                value = wb.Evaluate("=IF(TRUE,1,)");
+                Assert.AreEqual(1, value);
+
+                value = wb.Evaluate("=IF(FALSE,1,)");
+                Assert.AreEqual(false, value);
+
+                value = wb.Evaluate("=IF(FALSE,,2)");
+                Assert.AreEqual(2, value);
+            }
+        }
     }
 }