diff --git a/docs/BUILD b/docs/BUILD
index 30d53452..54a7b87e 100644
--- a/docs/BUILD
+++ b/docs/BUILD
@@ -58,6 +58,7 @@ proto_library(
         "//envoy/config/trace/v2:trace",
         "//envoy/config/transport_socket/capture/v2alpha:capture",
         "//envoy/data/accesslog/v2:accesslog",
+        "//envoy/data/core/v2alpha:health_check_event",
         "//envoy/data/tap/v2alpha:capture",
         "//envoy/service/accesslog/v2:als",
         "//envoy/service/auth/v2alpha:attribute_context",
diff --git a/envoy/api/v2/core/health_check.proto b/envoy/api/v2/core/health_check.proto
index 6c9077bd..92c811e9 100644
--- a/envoy/api/v2/core/health_check.proto
+++ b/envoy/api/v2/core/health_check.proto
@@ -185,6 +185,10 @@ message HealthCheck {
   //
   // The default value for "healthy edge interval" is the same as the default interval.
   google.protobuf.Duration healthy_edge_interval = 16;
+
+  // Specifies the path to the :ref:`health check event log <arch_overview_health_check_logging>`.
+  // If empty, no event log will be written.
+  string event_log_path = 17;
 }
 
 // Endpoint health status.
diff --git a/envoy/data/core/v2alpha/BUILD b/envoy/data/core/v2alpha/BUILD
new file mode 100644
index 00000000..740e4304
--- /dev/null
+++ b/envoy/data/core/v2alpha/BUILD
@@ -0,0 +1,15 @@
+load("//bazel:api_build_system.bzl", "api_proto_library")
+
+licenses(["notice"])  # Apache 2
+
+api_proto_library(
+    name = "health_check_event",
+    srcs = ["health_check_event.proto"],
+    visibility = [
+        "//visibility:public",
+    ],
+    deps = [
+        "//envoy/api/v2/core:address",
+        "//envoy/api/v2/core:base",
+    ],
+)
diff --git a/envoy/data/core/v2alpha/health_check_event.proto b/envoy/data/core/v2alpha/health_check_event.proto
new file mode 100644
index 00000000..5c9e28f6
--- /dev/null
+++ b/envoy/data/core/v2alpha/health_check_event.proto
@@ -0,0 +1,58 @@
+syntax = "proto3";
+
+package envoy.data.core.v2alpha;
+
+import "envoy/api/v2/core/address.proto";
+import "envoy/api/v2/core/base.proto";
+
+import "google/protobuf/duration.proto";
+import "google/protobuf/wrappers.proto";
+
+import "validate/validate.proto";
+import "gogoproto/gogo.proto";
+
+option (gogoproto.equal_all) = true;
+
+// [#protodoc-title: Health check logging events]
+// :ref:`Health check logging <arch_overview_health_check_logging>`.
+
+message HealthCheckEvent {
+  HealthCheckerType health_checker_type = 1 [(validate.rules).enum.defined_only = true];
+  envoy.api.v2.core.Address host = 2;
+  string cluster_name = 3 [(validate.rules).string.min_bytes = 1];
+
+  oneof event {
+    option (validate.required) = true;
+
+    // Host ejection.
+    HealthCheckEjectUnhealthy eject_unhealthy_event = 4;
+
+    // Host addition.
+    HealthCheckAddHealthy add_healthy_event = 5;
+  }
+}
+
+enum HealthCheckFailureType {
+  ACTIVE = 0;
+  PASSIVE = 1;
+  NETWORK = 2;
+}
+
+enum HealthCheckerType {
+  HTTP = 0;
+  TCP = 1;
+  GRPC = 2;
+  REDIS = 3;
+}
+
+message HealthCheckEjectUnhealthy {
+  // The type of failure that caused this ejection.
+  HealthCheckFailureType failure_type = 1 [(validate.rules).enum.defined_only = true];
+}
+
+message HealthCheckAddHealthy {
+  // Whether this addition is the result of the first ever health check on a host, in which case
+  // the configured :ref:`healthy threshold <envoy_api_field_core.HealthCheck.healthy_threshold>`
+  // is bypassed and the host is immediately added.
+  bool first_check = 1;
+}