Index: src/Boo.Lang.Parser/boo.g
===================================================================
--- src/Boo.Lang.Parser/boo.g	(revision 1773)
+++ src/Boo.Lang.Parser/boo.g	(working copy)
@@ -245,9 +245,9 @@
 		return LPAREN != token && LBRACK != token;
 	}
 	
-	static double ParseDouble(string text)
+	static double ParseDouble(string s)
 	{
-		return double.Parse(text, CultureInfo.InvariantCulture);
+		return double.Parse(s, NumberStyles.Float, CultureInfo.InvariantCulture);
 	}
 	
 	protected IntegerLiteralExpression ParseIntegerLiteralExpression(
@@ -260,11 +260,13 @@
 		if (s.StartsWith(HEX_PREFIX))
 		{
 			value = long.Parse(
-				s.Substring(HEX_PREFIX.Length), NumberStyles.AllowHexSpecifier, CultureInfo.InvariantCulture);
+				s.Substring(HEX_PREFIX.Length), NumberStyles.AllowHexSpecifier, 
+					CultureInfo.InvariantCulture);
 		}
 		else
 		{
-			value = long.Parse(s, CultureInfo.InvariantCulture);
+			value = long.Parse(s, NumberStyles.Integer | NumberStyles.AllowExponent,
+					CultureInfo.InvariantCulture);
 		}
 		return new IntegerLiteralExpression(ToLexicalInfo(token), value, isLong);
 	}
@@ -2569,16 +2571,24 @@
 INT : 
 	("0x"(HEXDIGIT)+)(('l' | 'L') { $setType(LONG); })? |
 	(DIGIT)+
+	(('e'|'E')('+'|'-')? (DIGIT)+)?
 	(
 		('l' | 'L') { $setType(LONG); } |
 		(
-			({BooLexer.IsDigit(LA(2))}? ('.' (DIGIT)+) { $setType(DOUBLE); })?
+			(
+				{BooLexer.IsDigit(LA(2))}? 
+				(
+					'.' (DIGIT)+
+					(('e'|'E')('+'|'-')? (DIGIT)+)?
+				)
+				{ $setType(DOUBLE); }
+			)?
 			(("ms" | 's' | 'm' | 'h' | 'd') { $setType(TIMESPAN); })?
 		)
 	)
 	;
 
-DOT : '.' ((DIGIT)+ {$setType(DOUBLE);})?;
+DOT : '.' ((DIGIT)+ (('e'|'E')('+'|'-')? (DIGIT)+)? {$setType(DOUBLE);})?;
 
 COLON : ':';
 
Index: src/Boo.Lang.Parser/booel.g
===================================================================
--- src/Boo.Lang.Parser/booel.g	(revision 1773)
+++ src/Boo.Lang.Parser/booel.g	(working copy)
@@ -61,16 +61,24 @@
 INT : 
 	("0x"(HEXDIGIT)+)(('l' | 'L') { $setType(LONG); })? |
 	(DIGIT)+
+	(('e'|'E')('+'|'-')? (DIGIT)+)?
 	(
 		('l' | 'L') { $setType(LONG); } |
 		(
-			({BooLexer.IsDigit(LA(2))}? ('.' (DIGIT)+) { $setType(DOUBLE); })?
+			(
+				{BooLexer.IsDigit(LA(2))}? 
+				(
+					'.' (DIGIT)+
+					(('e'|'E')('+'|'-')? (DIGIT)+)?
+				)
+				{ $setType(DOUBLE); }
+			)?
 			(("ms" | 's' | 'm' | 'h' | 'd') { $setType(TIMESPAN); })?
 		)
 	)
 	;
 
-DOT : '.' ((DIGIT)+ {$setType(DOUBLE);})?;
+DOT : '.' ((DIGIT)+ (('e'|'E')('+'|'-')? (DIGIT)+)? {$setType(DOUBLE);})?;
 
 COLON : ':';
 
Index: tests/testcases/compilation/exponential0.boo
===================================================================
--- tests/testcases/compilation/exponential0.boo	(revision 0)
+++ tests/testcases/compilation/exponential0.boo	(revision 0)
@@ -0,0 +1,53 @@
+"""
+100 System.Int32
+100 System.Int32
+110 System.Double
+0.011 System.Double
+100 System.Int64
+00:10:00 System.TimeSpan
+00:00:03.6000000 System.TimeSpan
+90 System.Double
+100
+100
+110
+0.011
+100
+00:10:00
+00:00:03.6000000
+90
+"""
+
+x = 1e+2
+print x, x.GetType() //100
+x2 = 1e2
+print x2, x2.GetType() //100
+x4 = 1.1e+2
+print x4, x4.GetType() //110
+x5 = 1.1e-2
+print x5, x5.GetType() //0.011
+x6 = 1e+2L
+print x6, x6.GetType() //100 long
+x7 = 6e+2s
+print x7, x7.GetType() //10:00
+x8 = 10.0e-4h
+print x8, x8.GetType()  //3.6 seconds
+x9 = .9e2
+print x9, x9.GetType() //90
+
+s = "${1e+2}"
+print s
+s2 = "${1e2}"
+print s2
+s4 = "${1.1e+2}"
+print s4
+s5 = "${1.1e-2}"
+print s5
+s6 = "${1e+2L}"
+print s6
+s7 = "${6e+2s}"
+print s7
+s8 = "${10.0e-4h}"
+print s8
+s9 = "${.9e2}"
+print s9
+