diff --git a/CHANGELOG.rst b/CHANGELOG.rst
index eb7aab5cc..934e58376 100644
--- a/CHANGELOG.rst
+++ b/CHANGELOG.rst
@@ -24,6 +24,8 @@ Added
    PATCH /api/kytos/core/dead_letter/ (requires request body)
    DELETE /api/kytos/core/dead_letter/ (requires request body)
 
+- Added ``tenacity`` as a core dependency for retries.
+
 Changed
 =======
 - Kytos controller can shutdown if the database is configured but not reachable during startup time.
diff --git a/requirements/dev.txt b/requirements/dev.txt
index f65f510fc..df8fa540a 100644
--- a/requirements/dev.txt
+++ b/requirements/dev.txt
@@ -233,6 +233,8 @@ traitlets==4.3.3
     # via
     #   -r requirements/run.txt
     #   ipython
+tenacity==8.0.1
+    # via -r requirements/run.txt
 typing-extensions==4.0.1
     # via
     #   -r requirements/run.txt
diff --git a/requirements/run.in b/requirements/run.in
index bcd775bdc..fa5a22be6 100644
--- a/requirements/run.in
+++ b/requirements/run.in
@@ -13,3 +13,4 @@ watchdog
 pyjwt
 pymongo==4.1.0
 pydantic==1.9.0
+tenacity==8.0.1
diff --git a/requirements/run.txt b/requirements/run.txt
index dd76cbb73..0c38c3f06 100644
--- a/requirements/run.txt
+++ b/requirements/run.txt
@@ -39,6 +39,7 @@ werkzeug==1.0.1           # via flask
 pydantic==1.9.0           # via -r requirements/run.in
 pymongo==4.1.0            # via -r requirements/run.in
 typing-extensions==4.0.1  # via pydantic
+tenacity==8.0.1           # via -r requirements/run.in
 
 # The following packages are considered to be unsafe in a requirements file:
 # setuptools
diff --git a/tox.ini b/tox.ini
index 0a96141bd..f40fc88ac 100644
--- a/tox.ini
+++ b/tox.ini
@@ -3,9 +3,6 @@ envlist = py36,py37,py38,py39
 
 [gh-actions]
 python =
-    3.6: py36
-    3.7: py37
-    3.8: py38
     3.9: py39
 
 [testenv]