diff --git a/src/changes/changes.xml b/src/changes/changes.xml
index f666427afb633b6dd102b6225a4671259ff1101b..da027e764e1a9532010c6a0340019e9bceab6e24 100644
--- a/src/changes/changes.xml
+++ b/src/changes/changes.xml
@@ -21,6 +21,10 @@
   </properties>
   <body>
     <release version="11.0" date="TBD" description="TBD">
+      <action dev="evan" type="update" issue="590">
+        Fix DateTimeComponents.toString(): correct ISO 8601, leap second, rounding issues.
+        Backwards incompatible.
+      </action>
       <action dev="bryan" type="update" issue="626">
         Used a separate Comparator for sorting integer least square solutions.
       </action>
diff --git a/src/main/java/org/orekit/time/DateTimeComponents.java b/src/main/java/org/orekit/time/DateTimeComponents.java
index 240a26d8dde8de3375411174b1fe172f5d51900e..4db7ba6ad1d6ce9e5128d5b44a9b8c8bd6a38918 100644
--- a/src/main/java/org/orekit/time/DateTimeComponents.java
+++ b/src/main/java/org/orekit/time/DateTimeComponents.java
@@ -235,7 +235,7 @@ public class DateTimeComponents implements Serializable, Comparable<DateTimeComp
      * @return string representation of this pair
      */
     public String toString() {
-        return toString(60);
+        return toStringRfc3339();
     }
 
     /** Return a string representation of this pair.
diff --git a/src/test/java/org/orekit/time/AbsoluteDateTest.java b/src/test/java/org/orekit/time/AbsoluteDateTest.java
index dc34462fa5acf39e352060021deb7c4247f2c3d3..95ceb1e374fc83a49437dfceed56a98ec6553683 100644
--- a/src/test/java/org/orekit/time/AbsoluteDateTest.java
+++ b/src/test/java/org/orekit/time/AbsoluteDateTest.java
@@ -1174,6 +1174,8 @@ public class AbsoluteDateTest {
                 CoreMatchers.is(s));
         MatcherAssert.assertThat(d.getComponents(utc).toStringRfc3339(),
                 CoreMatchers.is(s));
+        MatcherAssert.assertThat(d.getComponents(utc).toString(),
+                CoreMatchers.is(s));
     }
 
 
@@ -1281,12 +1283,6 @@ public class AbsoluteDateTest {
 
     private void checkToString(final AbsoluteDate d, final String s) {
         MatcherAssert.assertThat(d.toString(), CoreMatchers.is(s));
-        // there is no way for the second form here to know whether it is in a leap second
-        // or not so it makes poor choices regarding rounding during a leap second.
-        // Only check it when not during a leap second.
-        if (s.charAt(s.length() - 6) != '6') {
-            MatcherAssert.assertThat(d.getComponents(utc).toString(), CoreMatchers.is(s));
-        }
     }
 
     @Before
diff --git a/src/test/java/org/orekit/time/DateTimeComponentsTest.java b/src/test/java/org/orekit/time/DateTimeComponentsTest.java
index c6f932e0660c117f546fe393b653187c2f3fc118..bf482a779125a9e788d73f44e5aa77a3a8119477 100644
--- a/src/test/java/org/orekit/time/DateTimeComponentsTest.java
+++ b/src/test/java/org/orekit/time/DateTimeComponentsTest.java
@@ -22,6 +22,7 @@ import org.hamcrest.MatcherAssert;
 import org.hipparchus.util.FastMath;
 import org.junit.Assert;
 import org.junit.Test;
+import org.orekit.Utils;
 
 
 public class DateTimeComponentsTest {
@@ -73,7 +74,7 @@ public class DateTimeComponentsTest {
     public void testString() {
         final DateTimeComponents date =
             new DateTimeComponents(DateComponents.J2000_EPOCH, TimeComponents.H12);
-        Assert.assertEquals("2000-01-01T12:00:00.000", date.toString());
+        Assert.assertEquals("2000-01-01T12:00:00Z", date.toString());
     }
 
     @Test
@@ -86,7 +87,7 @@ public class DateTimeComponentsTest {
 
     @Test
     public void testParse() {
-        String s = "2000-01-02T03:04:05.000";
+        String s = "2000-01-02T03:04:05-01:05";
         Assert.assertEquals(s, DateTimeComponents.parseDateTime(s).toString());
     }
 
@@ -151,4 +152,29 @@ public class DateTimeComponentsTest {
         MatcherAssert.assertThat(actual.toStringRfc3339(), CoreMatchers.is(expected));
     }
 
+    /**
+     * Check {@link DateTimeComponents#toString()} for leap second and rounding issues.
+     * See #591.
+     */
+    @Test
+    public void testToString() {
+        Utils.setDataRoot("regular-data");
+        TimeScale utc = TimeScalesFactory.getUTC();
+        // latest leap second in the file
+        AbsoluteDate d = new AbsoluteDate("2015-07-01", utc).shiftedBy(-0.5);
+        DateTimeComponents dtc = d.getComponents(utc);
+        Assert.assertEquals(dtc.toString(), "2015-06-30T23:59:60.5Z");
+        // first leap second and change
+        d = new AbsoluteDate("1961-01-01", utc).shiftedBy(-0.1);
+        dtc = d.getComponents(utc);
+        Assert.assertEquals(dtc.toString(), "1960-12-31T23:59:61.32281798015773Z");
+        // test rounding
+        d = new AbsoluteDate("2014-02-02", utc).shiftedBy(-FastMath.ulp(1.0));
+        dtc = d.getComponents(utc);
+        Assert.assertEquals(dtc.toString(), "2014-02-01T23:59:59.99999999999999Z");
+        // test time zone
+        dtc = new DateTimeComponents(dtc.getDate(), new TimeComponents(1, 2, 3, 456));
+        Assert.assertEquals(dtc.toString(), "2014-02-01T01:02:03+07:36");
+    }
+
 }
