diff --git a/api-webapp/src/main/kotlin/org/jeudego/pairgoth/api/ResultsHandler.kt b/api-webapp/src/main/kotlin/org/jeudego/pairgoth/api/ResultsHandler.kt
index 35f1a5e..daef968 100644
--- a/api-webapp/src/main/kotlin/org/jeudego/pairgoth/api/ResultsHandler.kt
+++ b/api-webapp/src/main/kotlin/org/jeudego/pairgoth/api/ResultsHandler.kt
@@ -27,4 +27,14 @@ object ResultsHandler: PairgothApiHandler {
         tournament.dispatchEvent(Event.ResultUpdated, request, Json.Object("round" to round, "data" to game))
         return Json.Object("success" to true)
     }
+
+    override fun delete(request: HttpServletRequest, response: HttpServletResponse): Json {
+        val tournament = getTournament(request)
+        val round = getSubSelector(request)?.toIntOrNull() ?: badRequest("invalid round number")
+        for (game in tournament.games(round).values) {
+            game.result = Game.Result.UNKNOWN
+        }
+        tournament.dispatchEvent(Event.ResultsCleared, request, Json.Object("round" to round))
+        return Json.Object("success" to true)
+    }
 }
diff --git a/api-webapp/src/main/kotlin/org/jeudego/pairgoth/server/Event.kt b/api-webapp/src/main/kotlin/org/jeudego/pairgoth/server/Event.kt
index 57147ee..82fa26d 100644
--- a/api-webapp/src/main/kotlin/org/jeudego/pairgoth/server/Event.kt
+++ b/api-webapp/src/main/kotlin/org/jeudego/pairgoth/server/Event.kt
@@ -17,6 +17,7 @@ enum class Event {
     GamesDeleted,
     GameUpdated,
     ResultUpdated,
+    ResultsCleared,
     TablesRenumbered
     ;
 
diff --git a/doc/API.md b/doc/API.md
index 4a079a8..d40645e 100644
--- a/doc/API.md
+++ b/doc/API.md
@@ -17,7 +17,7 @@ POST, PUT and DELETE requests return either the 200 HTTP code with `{ "success":
 + /api/tour/#tid/team      GET POST            Team handling
 + /api/tour/#tid/team/#tid GET PUT DELETE      Team handling
 + /api/tour/#tid/pair/#rn  GET POST PUT DELETE Pairing
-+ /api/tour/#tid/res/#rn   GET PUT             Results
++ /api/tour/#tid/res/#rn   GET PUT DELETE      Results
 + /api/tour/#tid/standings GET                 Standings
 + /api/tour/#tid/stand/#rn GET                 Standings
 
@@ -136,6 +136,12 @@ POST, PUT and DELETE requests return either the 200 HTTP code with `{ "success":
  
     *output* `{ "success": true }`
 
++ `DELETE /api/tour/#tip/res/#rn` Clear all results (put back all results to unknown)
+
+  *input* none
+
+  *output* `{ "success": true }`
+
 ## Standings
 
 + `GET /api/tour/#tid/stand/#rn` Get standings after round #rn (or initial standings for round '0')
diff --git a/view-webapp/src/main/webapp/js/tour-results.inc.js b/view-webapp/src/main/webapp/js/tour-results.inc.js
index 04f6c79..ef0ddd3 100644
--- a/view-webapp/src/main/webapp/js/tour-results.inc.js
+++ b/view-webapp/src/main/webapp/js/tour-results.inc.js
@@ -41,6 +41,15 @@ function setResult(id, result, previous) {
     })
 }
 
+function clearResults() {
+  api.deleteJson(`tour/${tour_id}/res/${activeRound}`)
+    .then(res => {
+      if (res !== 'error') {
+        document.location.reload();
+      }
+    })
+}
+
 const results = [ '?', 'w', 'b', '=', 'X', '#', '0' ];
 
 onLoad(()=>{
@@ -70,4 +79,9 @@ onLoad(()=>{
       $('#results-table tbody tr').removeClass('filtered');
     }
   });
+  $('#clear-results').on('click', e => {
+    if (confirm($('#confirmation')[0].textContent)) {
+      clearResults();
+    }
+  });
 });
diff --git a/view-webapp/src/main/webapp/tour-results.inc.html b/view-webapp/src/main/webapp/tour-results.inc.html
index e7c84c1..a95ba5f 100644
--- a/view-webapp/src/main/webapp/tour-results.inc.html
+++ b/view-webapp/src/main/webapp/tour-results.inc.html
@@ -39,4 +39,13 @@
       </tbody>
     </table>
   </div>
+  <div class="form-actions">
+    <button id="clear-results" class="ui orange right labeled icon floating info button">
+      <i class="trash icon"></i>
+      Clear results
+    </button>
+  </div>
+</div>
+<div id="confirmation" class="hidden">
+  Clear all results for round <span>$round</span> ?
 </div>