diff --git a/openapi3filter/validate_readonly_test.go b/openapi3filter/validate_readonly_test.go
index 454a927e9..8b7ccb7ef 100644
--- a/openapi3filter/validate_readonly_test.go
+++ b/openapi3filter/validate_readonly_test.go
@@ -3,6 +3,7 @@ package openapi3filter
 import (
 	"bytes"
 	"encoding/json"
+	"io/ioutil"
 	"net/http"
 	"testing"
 
@@ -26,6 +27,16 @@ func TestValidatingRequestBodyWithReadOnlyProperty(t *testing.T) {
     "/accounts": {
       "post": {
         "description": "Create a new account",
+        "parameters": [
+          {
+            "in": "query",
+            "name": "q",
+            "schema": {
+              "type": "string",
+              "default": "Q"
+            }
+          }
+        ],
         "requestBody": {
           "required": true,
           "content": {
@@ -34,6 +45,10 @@ func TestValidatingRequestBodyWithReadOnlyProperty(t *testing.T) {
                 "type": "object",
                 "required": ["_id"],
                 "properties": {
+                  "_": {
+                    "type": "boolean",
+                    "default": false
+                  },
                   "_id": {
                     "type": "string",
                     "description": "Unique identifier for this object.",
@@ -61,10 +76,6 @@ func TestValidatingRequestBodyWithReadOnlyProperty(t *testing.T) {
 }
 `
 
-	type Request struct {
-		ID string `json:"_id"`
-	}
-
 	sl := openapi3.NewLoader()
 	doc, err := sl.LoadFromData([]byte(spec))
 	require.NoError(t, err)
@@ -73,7 +84,12 @@ func TestValidatingRequestBodyWithReadOnlyProperty(t *testing.T) {
 	router, err := legacyrouter.NewRouter(doc)
 	require.NoError(t, err)
 
-	b, err := json.Marshal(Request{ID: "bt6kdc3d0cvp6u8u3ft0"})
+	b, err := json.Marshal(struct {
+		Blank bool   `json:"_,omitempty"`
+		ID    string `json:"_id"`
+	}{
+		ID: "bt6kdc3d0cvp6u8u3ft0",
+	})
 	require.NoError(t, err)
 
 	httpReq, err := http.NewRequest(http.MethodPost, "/accounts", bytes.NewReader(b))
@@ -89,4 +105,12 @@ func TestValidatingRequestBodyWithReadOnlyProperty(t *testing.T) {
 		Route:      route,
 	})
 	require.NoError(t, err)
+
+	// Unset default values in body were set
+	validatedReqBody, err := ioutil.ReadAll(httpReq.Body)
+	require.NoError(t, err)
+	require.JSONEq(t, `{"_":false,"_id":"bt6kdc3d0cvp6u8u3ft0"}`, string(validatedReqBody))
+	// Unset default values in URL were set
+	// Unset default values in headers were set
+	// Unset default values in cookies were set
 }
diff --git a/openapi3filter/validate_request.go b/openapi3filter/validate_request.go
index 990b299ef..5e5a0e6a5 100644
--- a/openapi3filter/validate_request.go
+++ b/openapi3filter/validate_request.go
@@ -52,7 +52,6 @@ func ValidateRequest(ctx context.Context, input *RequestValidationInput) error {
 		if err = ValidateParameter(ctx, input, parameter); err != nil && !options.MultiError {
 			return err
 		}
-
 		if err != nil {
 			me = append(me, err)
 		}
@@ -63,7 +62,6 @@ func ValidateRequest(ctx context.Context, input *RequestValidationInput) error {
 		if err = ValidateParameter(ctx, input, parameter.Value); err != nil && !options.MultiError {
 			return err
 		}
-
 		if err != nil {
 			me = append(me, err)
 		}
@@ -75,7 +73,6 @@ func ValidateRequest(ctx context.Context, input *RequestValidationInput) error {
 		if err = ValidateRequestBody(ctx, input, requestBody.Value); err != nil && !options.MultiError {
 			return err
 		}
-
 		if err != nil {
 			me = append(me, err)
 		}
@@ -92,7 +89,6 @@ func ValidateRequest(ctx context.Context, input *RequestValidationInput) error {
 		if err = ValidateSecurityRequirements(ctx, input, *security); err != nil && !options.MultiError {
 			return err
 		}
-
 		if err != nil {
 			me = append(me, err)
 		}
@@ -137,6 +133,12 @@ func ValidateParameter(ctx context.Context, input *RequestValidationInput, param
 		}
 		schema = parameter.Schema.Value
 	}
+
+	// Maybe use default value
+	if value == nil && schema != nil {
+		value = schema.Default
+	}
+
 	// Validate a parameter's value.
 	if value == nil {
 		if parameter.Required {