diff --git a/matrix-sdk-android/src/androidTest/java/org/matrix/android/sdk/session/room/timeline/TimelineWithManyMembersTest.kt b/matrix-sdk-android/src/androidTest/java/org/matrix/android/sdk/session/room/timeline/TimelineWithManyMembersTest.kt
new file mode 100644
index 0000000000..a0271cb5b9
--- /dev/null
+++ b/matrix-sdk-android/src/androidTest/java/org/matrix/android/sdk/session/room/timeline/TimelineWithManyMembersTest.kt
@@ -0,0 +1,94 @@
+/*
+ * Copyright (c) 2020 New Vector Ltd
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.matrix.android.sdk.session.room.timeline
+
+import org.junit.FixMethodOrder
+import org.junit.Test
+import org.junit.runner.RunWith
+import org.junit.runners.JUnit4
+import org.junit.runners.MethodSorters
+import org.matrix.android.sdk.InstrumentedTest
+import org.matrix.android.sdk.api.extensions.orFalse
+import org.matrix.android.sdk.api.session.events.model.toModel
+import org.matrix.android.sdk.api.session.room.model.message.MessageContent
+import org.matrix.android.sdk.api.session.room.timeline.TimelineSettings
+import org.matrix.android.sdk.common.CommonTestHelper
+import org.matrix.android.sdk.common.CryptoTestHelper
+import java.util.concurrent.CountDownLatch
+
+@RunWith(JUnit4::class)
+@FixMethodOrder(MethodSorters.JVM)
+class TimelineWithManyMembersTest : InstrumentedTest {
+
+    private val commonTestHelper = CommonTestHelper(context())
+    private val cryptoTestHelper = CryptoTestHelper(commonTestHelper)
+
+    /**
+     * Ensures when someone sends a message to a crowded room, everyone can decrypt the message.
+     */
+    @Test
+    fun everyoneShouldDecryptMessage3Members() {
+        val cryptoTestData = cryptoTestHelper.doE2ETestWithAliceAndBobAndSamInARoom()
+
+        val aliceSession = cryptoTestData.firstSession
+        val bobSession = cryptoTestData.secondSession!!
+        val samSession = cryptoTestData.thirdSession!!
+
+        val aliceRoomId = cryptoTestData.roomId
+
+        aliceSession.cryptoService().setWarnOnUnknownDevices(false)
+        bobSession.cryptoService().setWarnOnUnknownDevices(false)
+        samSession.cryptoService().setWarnOnUnknownDevices(false)
+
+        val roomFromAlicePOV = aliceSession.getRoom(aliceRoomId)!!
+        val roomFromBobPOV = bobSession.getRoom(aliceRoomId)!!
+        val roomFromSamPOV = samSession.getRoom(aliceRoomId)!!
+
+        val bobTimeline = roomFromBobPOV.createTimeline(null, TimelineSettings(30))
+        val samTimeline = roomFromSamPOV.createTimeline(null, TimelineSettings(30))
+        bobTimeline.start()
+        samTimeline.start()
+
+        val firstMessage = "First messages from Alice"
+        commonTestHelper.sendTextMessage(
+                roomFromAlicePOV,
+                firstMessage,
+                1)
+
+        bobSession.startSync(true)
+        run {
+            val lock = CountDownLatch(1)
+            val eventsListener = commonTestHelper.createEventListener(lock) { snapshot ->
+                snapshot.firstOrNull()?.root?.getClearContent()?.toModel<MessageContent>()?.body?.startsWith(firstMessage).orFalse()
+            }
+            bobTimeline.addListener(eventsListener)
+            commonTestHelper.await(lock)
+        }
+        bobSession.stopSync()
+
+        samSession.startSync(true)
+        run {
+            val lock = CountDownLatch(1)
+            val eventsListener = commonTestHelper.createEventListener(lock) { snapshot ->
+                snapshot.firstOrNull()?.root?.getClearContent()?.toModel<MessageContent>()?.body?.startsWith(firstMessage).orFalse()
+            }
+            samTimeline.addListener(eventsListener)
+            commonTestHelper.await(lock)
+        }
+        samSession.stopSync()
+    }
+}