diff --git a/docs/reference/migration/migrate_6_0/plugins.asciidoc b/docs/reference/migration/migrate_6_0/plugins.asciidoc
index 9f68f55472d..7d21ac361bc 100644
--- a/docs/reference/migration/migrate_6_0/plugins.asciidoc
+++ b/docs/reference/migration/migrate_6_0/plugins.asciidoc
@@ -73,3 +73,10 @@ and `cloud.aws.ec2.region`. Instead, specify the full endpoint.
 
 Previous versions of Elasticsearch would skip hidden files and directories when
 scanning the plugins folder. This leniency has been removed.
+
+==== ICU Analysis plugin
+
+The icu4j library has been upgraded to 59.1,
+Indices created in the previous major version will need to be reindexed
+in order to return correct (and correctly ordered) results,
+and to take advantage of new characters.
diff --git a/plugins/analysis-icu/build.gradle b/plugins/analysis-icu/build.gradle
index a25c2c771ff..2a8905e080f 100644
--- a/plugins/analysis-icu/build.gradle
+++ b/plugins/analysis-icu/build.gradle
@@ -24,7 +24,7 @@ esplugin {
 
 dependencies {
   compile "org.apache.lucene:lucene-analyzers-icu:${versions.lucene}"
-  compile 'com.ibm.icu:icu4j:56.1'
+  compile 'com.ibm.icu:icu4j:59.1'
 }
 
 dependencyLicenses {
diff --git a/plugins/analysis-icu/licenses/icu4j-56.1.jar.sha1 b/plugins/analysis-icu/licenses/icu4j-56.1.jar.sha1
deleted file mode 100644
index 51dc722bf92..00000000000
--- a/plugins/analysis-icu/licenses/icu4j-56.1.jar.sha1
+++ /dev/null
@@ -1 +0,0 @@
-8dd6671f52165a0419e6de5e1016400875a90fa9
\ No newline at end of file
diff --git a/plugins/analysis-icu/licenses/icu4j-59.1.jar.sha1 b/plugins/analysis-icu/licenses/icu4j-59.1.jar.sha1
new file mode 100644
index 00000000000..5401f914f58
--- /dev/null
+++ b/plugins/analysis-icu/licenses/icu4j-59.1.jar.sha1
@@ -0,0 +1 @@
+6f06e820cf4c8968bbbaae66ae0b33f6a256b57f
\ No newline at end of file