diff --git a/README.md b/README.md
index ed3cd9c..ac04dd7 100644
--- a/README.md
+++ b/README.md
@@ -73,6 +73,8 @@ zm_repo:
 ```
 * **disable_existing_dns_stub_listener:** Inform "y" to disable the systemd-resolved DNS stub listener and free up port 53. Default: **n**
 
+* **zimbra_upgrade:** Inform "y" to upgrade an existing Zimbra installation. Zimbra will be upgraded to **zimbra_version** version. Default: **n**
+
 Service Variables - Inform "y" or "n"
 --------------
 
diff --git a/defaults/main.yml b/defaults/main.yml
index f819fa1..670ab97 100644
--- a/defaults/main.yml
+++ b/defaults/main.yml
@@ -39,9 +39,10 @@ zmnetwork: "192.168.200.0/8"
 timezone: UTC
 #hosts_lines:
 #  - "198.162.1.3 {{ hostname }}.{{ domain }} {{ hostname }}" 
+disable_existing_dns_stub_listener: n
 
 #
-# Zimbra repository
+# Zimbra installers
 ################################################################################
 zimbra_version: 8.8.15
 
@@ -62,4 +63,5 @@ zm_repo:
         6: zcs-8.8.15_GA_3869.RHEL6_64.20190918004220
         7: zcs-8.8.15_GA_3869.RHEL7_64.20190918004220
         8: zcs-8.8.15_GA_3953.RHEL8_64.20200629025823
-disable_existing_dns_stub_listener: n
+
+zimbra_upgrade: false
\ No newline at end of file
diff --git a/tasks/install/zimbra.yml b/tasks/install/zimbra.yml
index 5f07580..6658fc8 100644
--- a/tasks/install/zimbra.yml
+++ b/tasks/install/zimbra.yml
@@ -29,7 +29,7 @@
 
 - name: Uploading keystroke file
   template:
-    src: 'installZimbra-keystrokes'
+    src: "{{ 'installZimbra-keystrokes' if not zimbra_upgrade else 'installZimbraUpgrade-keystrokes' }}"
     dest: /tmp/zcs/installZimbra-keystrokes
     owner: root
     group: root
@@ -37,7 +37,7 @@
 
 - name: Uploading installer configuration file
   template:
-    src: 'installZimbraScript.j2'
+    src: "{{ 'installZimbraScript.j2' if not zimbra_upgrade else 'installZimbraScriptUpgrade.j2' }}"
     dest: /tmp/zcs/installZimbraScript
     owner: root
     group: root
diff --git a/tasks/main.yml b/tasks/main.yml
index f577fe9..7a417bc 100644
--- a/tasks/main.yml
+++ b/tasks/main.yml
@@ -11,9 +11,9 @@
 # Installation process
 ################################################################################
 - import_tasks: 'install/dependencies.yml'
-  when: getent_passwd.rc == 2
+  when: getent_passwd.rc == 2 or zimbra_upgrade
 - import_tasks: 'install/zimbra.yml'
-  when: getent_passwd.rc == 2
+  when: getent_passwd.rc == 2 or zimbra_upgrade
 - import_tasks: 'install/policyd.yml'
   when: zimbra_policyd == 'y'
 
@@ -21,11 +21,11 @@
 # Configuration process
 ################################################################################
 - import_tasks: 'configure/proxy.yml'
-  when: zimbra_proxy == 'y'
+  when: zimbra_proxy == 'y' and not zimbra_upgrade
 - import_tasks: 'configure/mailbox.yml'
-  when: zimbra_store == 'y'
+  when: zimbra_store == 'y' and not zimbra_upgrade
 - import_tasks: 'configure/mta.yml'
-  when: zimbra_mta == 'y'
+  when: zimbra_mta == 'y' and not zimbra_upgrade
 - import_tasks: 'configure/disable_existing_dns_stub_listener.yml'
   when: zimbra_dnscache == 'y' and disable_existing_dns_stub_listener == 'y'
 
diff --git a/templates/installZimbraScriptUpgrade.j2 b/templates/installZimbraScriptUpgrade.j2
new file mode 100644
index 0000000..8d584ce
--- /dev/null
+++ b/templates/installZimbraScriptUpgrade.j2
@@ -0,0 +1 @@
+zimbraNotifyInstall=no
\ No newline at end of file
diff --git a/templates/installZimbraUpgrade-keystrokes b/templates/installZimbraUpgrade-keystrokes
new file mode 100644
index 0000000..3524cf2
--- /dev/null
+++ b/templates/installZimbraUpgrade-keystrokes
@@ -0,0 +1,5 @@
+y
+n
+y
+y
+y
\ No newline at end of file