--- a/toolkit/components/telemetry/Histograms.json
+++ b/toolkit/components/telemetry/Histograms.json
@@ -4122,16 +4122,34 @@
   "URLCLASSIFIER_PREFIX_MATCH": {
     "alert_emails": ["safebrowsing-telemetry@mozilla.org"],
     "expires_in_version": "58",
     "kind": "enumerated",
     "n_values": 4,
     "bug_numbers": [1298257],
     "description": "Classifier prefix matching result (0 = no match, 1 = match only V2, 2 = match only V4, 3 = match both V2 and V4)"
   },
+  "URLCLASSIFIER_POSITIVE_CACHE_DURATION": {
+    "alert_emails": ["safebrowsing-telemetry@mozilla.org"],
+    "expires_in_version": "60",
+    "kind": "exponential",
+    "high": 86400000,
+    "n_buckets": 50,
+    "bug_numbers": [1338082],
+    "description": "Positive cache duration (ms) received in fullhash response from any v4 provider"
+  },
+  "URLCLASSIFIER_NEGATIVE_CACHE_DURATION": {
+    "alert_emails": ["safebrowsing-telemetry@mozilla.org"],
+    "expires_in_version": "60",
+    "kind": "exponential",
+    "high": 86400000,
+    "n_buckets": 50,
+    "bug_numbers": [1338082],
+    "description": "Negative cache duration (ms) received in fullhash response from any v4 provider"
+  },
   "CSP_DOCUMENTS_COUNT": {
     "alert_emails": ["seceng@mozilla.com"],
     "bug_numbers": [1252829],
     "expires_in_version": "55",
     "kind": "count",
     "description": "Number of unique pages that contain a CSP"
   },
   "CSP_UNSAFE_INLINE_DOCUMENTS_COUNT": {

--- a/toolkit/components/url-classifier/nsUrlClassifierUtils.cpp
+++ b/toolkit/components/url-classifier/nsUrlClassifierUtils.cpp
@@ -450,29 +450,35 @@ nsUrlClassifierUtils::ParseFindFullHashR
   for (auto& m : r.matches()) {
     nsCString tableNames;
     nsresult rv = ConvertThreatTypeToListNames(m.threat_type(), tableNames);
     if (NS_FAILED(rv)) {
       hasUnknownThreatType = true;
       continue; // Ignore un-convertable threat type.
     }
     auto& hash = m.threat().hash();
+    auto cacheDuration = DurationToMs(m.cache_duration());
     aCallback->OnCompleteHashFound(nsCString(hash.c_str(), hash.length()),
-                                   tableNames,
-                                   DurationToMs(m.cache_duration()));
+                                   tableNames, cacheDuration);
+
+    Telemetry::Accumulate(Telemetry::URLCLASSIFIER_POSITIVE_CACHE_DURATION,
+                          cacheDuration);
   }
 
   auto minWaitDuration = DurationToMs(r.minimum_wait_duration());
   auto negCacheDuration = DurationToMs(r.negative_cache_duration());
 
   aCallback->OnResponseParsed(minWaitDuration, negCacheDuration);
 
   Telemetry::Accumulate(Telemetry::URLCLASSIFIER_COMPLETION_ERROR,
                         hasUnknownThreatType ? UNKNOWN_THREAT_TYPE : SUCCESS);
 
+  Telemetry::Accumulate(Telemetry::URLCLASSIFIER_NEGATIVE_CACHE_DURATION,
+                        negCacheDuration);
+
   return NS_OK;
 }
 
 //////////////////////////////////////////////////////////
 // nsIObserver
 
 NS_IMETHODIMP
 nsUrlClassifierUtils::Observe(nsISupports *aSubject, const char *aTopic,