diff --git a/ChangeLog b/ChangeLog
index 9970b5dea2..5d722bd9fd 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,10 @@
+Fri Nov 16 23:31:18 2007  Yukihiro Matsumoto  <matz@ruby-lang.org>
+
+	* bignum.c (rb_big_odd_p): new method added.  a patch from Tadashi
+	  Saito <shiba AT mail2.accsnet.ne.jp>.  [ruby-dev:32305]
+
+	* bignum.c (rb_big_even_p): ditto.
+
 Fri Nov 16 17:41:34 2007  Nobuyoshi Nakada  <nobu@ruby-lang.org>
 
 	* ext/iconv/iconv.c (Document-class): moved the simplest example to
diff --git a/bignum.c b/bignum.c
index 138922c417..71e0fb8da7 100644
--- a/bignum.c
+++ b/bignum.c
@@ -2431,6 +2431,38 @@ rb_big_size(VALUE big)
     return LONG2FIX(RBIGNUM_LEN(big)*SIZEOF_BDIGITS);
 }
 
+/*
+ *  call-seq:
+ *     big.odd? -> true or false
+ *
+ *  Returns <code>true</code> if <i>big</i> is an odd number.
+ */
+
+static VALUE
+rb_big_odd_p(VALUE num)
+{
+    if (BDIGITS(num)[0] & 1) {
+       return Qtrue;
+    }
+    return Qfalse;
+}
+
+/*
+ *  call-seq:
+ *     big.even? -> true or false
+ *
+ *  Returns <code>true</code> if <i>big</i> is an even number.
+ */
+
+static VALUE
+rb_big_even_p(VALUE num)
+{
+    if (BDIGITS(num)[0] & 1) {
+       return Qfalse;
+    }
+    return Qtrue;
+}
+
 /*
  *  Bignum objects hold integers outside the range of
  *  Fixnum. Bignum objects are created
@@ -2484,6 +2516,8 @@ Init_Bignum(void)
     rb_define_method(rb_cBignum, "to_f", rb_big_to_f, 0);
     rb_define_method(rb_cBignum, "abs", rb_big_abs, 0);
     rb_define_method(rb_cBignum, "size", rb_big_size, 0);
+    rb_define_method(rb_cBignum, "odd?", rb_big_odd_p, 0);
+    rb_define_method(rb_cBignum, "even?", rb_big_even_p, 0);
 
     power_cache_init();
 }