diff --git a/README b/README
index 6a49eab..369e10b 100644
--- a/README
+++ b/README
@@ -18,7 +18,7 @@
 	Accept-Language, Accept-Charset, Max-Forwards, If-Match,
 	If-None-Match, Last-Modified, Content-Length, Expires,
 	Content-Language, Content-Encoding, Allow, Host, Accept,
-	Connection, Content-Range
+	Connection, Content-Range, User-Agent
 
 Report Bugs
 	Create a ticket on the issue tracking interface of GitHub:
diff --git a/ngx_http_header_inspect.c b/ngx_http_header_inspect.c
index 283e193..7cb350c 100644
--- a/ngx_http_header_inspect.c
+++ b/ngx_http_header_inspect.c
@@ -39,6 +39,7 @@
 static ngx_int_t ngx_header_inspect_accept_header(ngx_header_inspect_loc_conf_t *conf, ngx_log_t *log, ngx_str_t value);
 static ngx_int_t ngx_header_inspect_connection_header(ngx_header_inspect_loc_conf_t *conf, ngx_log_t *log, ngx_str_t value);
 static ngx_int_t ngx_header_inspect_contentrange_header(ngx_header_inspect_loc_conf_t *conf, ngx_log_t *log, ngx_str_t value);
+static ngx_int_t ngx_header_inspect_useragent_header(ngx_header_inspect_loc_conf_t *conf, ngx_log_t *log, ngx_str_t value);
 static ngx_int_t ngx_header_inspect_ifrange_header(ngx_header_inspect_loc_conf_t *conf, ngx_log_t *log, ngx_str_t value);
 static ngx_int_t ngx_header_inspect_date_header(ngx_header_inspect_loc_conf_t *conf, ngx_log_t *log, char *header, ngx_str_t value);
 static ngx_int_t ngx_header_inspect_process_request(ngx_http_request_t *r);
@@ -1434,6 +1435,114 @@
 	return rc;
 }
 
+static ngx_int_t ngx_header_inspect_useragent_header(ngx_header_inspect_loc_conf_t *conf, ngx_log_t *log, ngx_str_t value) {
+	ngx_uint_t i = 0;
+	u_char d;
+	ngx_int_t rc = NGX_OK;
+	enum useragent_header_states { UAS_START, UAS_PROD, UAS_SLASH, UAS_VER, UAS_SPACE, UAS_PAREN } state;
+
+
+	if ( value.len < 1 ) {
+		if ( conf->log ) {
+			ngx_log_error(NGX_LOG_ALERT, log, 0, "header_inspect: User-Agent header \"%s\" too short", value.data);
+		}
+		return NGX_ERROR;
+	}
+
+	state = UAS_START;
+	for ( i = 0; i < value.len ; i++ ) {
+		d = value.data[i];
+		if (
+			((d >= '0') && (d <= '9')) ||
+			((d >= 'a') && (d <= 'z')) ||
+			((d >= 'A') && (d <= 'Z')) ||
+			(d == '-') || (d == '.')
+		) {
+			switch ( state ) {
+				case UAS_START:
+				case UAS_SPACE:
+					state = UAS_PROD;
+					break;
+				case UAS_PROD:
+				case UAS_VER:
+				case UAS_PAREN:
+					break;
+				case UAS_SLASH:
+					state = UAS_VER;
+					break;
+				default:
+					rc = NGX_ERROR;
+			}
+		} else if ( d == '/' ) {
+			switch ( state ) {
+				case UAS_PROD:
+					state = UAS_SLASH;
+					break;
+				default:
+					rc = NGX_ERROR;
+			}
+		} else if ( d == ' ' ) {
+			switch ( state ) {
+				case UAS_VER:
+					state = UAS_SPACE;
+					break;
+				case UAS_SPACE:
+				case UAS_PAREN:
+					break;
+				default:
+					rc = NGX_ERROR;
+			}
+		} else if ( d == '(' ) {
+			switch ( state ) {
+				case UAS_SPACE:
+					state = UAS_PAREN;
+					break;
+				default:
+					rc = NGX_ERROR;
+			}
+		} else if ( d == ')' ) {
+			switch ( state ) {
+				case UAS_PAREN:
+					state = UAS_SPACE;
+					break;
+				default:
+					rc = NGX_ERROR;
+			}
+		} else if (
+			(d == ',') || (d == ':') || (d == ';') ||
+			(d == '+') || (d == '_')
+		) {
+			switch ( state ) {
+				case UAS_PAREN:
+					break;
+				default:
+					rc = NGX_ERROR;
+			}
+		} else {
+			rc = NGX_ERROR;
+		}
+		if ( rc == NGX_ERROR ) {
+			if ( conf->log ) {
+				ngx_log_error(NGX_LOG_ALERT, log, 0, "header_inspect: illegal character at position %d in User-Agent header \"%s\"", i, value.data);
+			}
+			return NGX_ERROR;
+		}
+	}
+	switch ( state ) {
+		case UAS_SPACE:
+		case UAS_PROD:
+		case UAS_VER:
+			break;
+		default:
+			if ( conf->log ) {
+				ngx_log_error(NGX_LOG_ALERT, log, 0, "header_inspect: unexpected end of User-Agent header \"%s\"", value.data);
+			}
+			return NGX_ERROR;
+	}
+
+	return NGX_OK;
+}
+
 static ngx_int_t ngx_header_inspect_contentrange_header(ngx_header_inspect_loc_conf_t *conf, ngx_log_t *log, ngx_str_t value) {
 	ngx_uint_t i = 0;
 	ngx_int_t rc = NGX_OK;
@@ -1996,6 +2105,11 @@
 					if ((rc != NGX_OK) && conf->block) {
 						return NGX_HTTP_BAD_REQUEST;
 					}
+				} else if ((h[i].key.len == 10) && (ngx_strcmp("User-Agent", h[i].key.data) == 0) ) {
+					rc = ngx_header_inspect_useragent_header(conf, r->connection->log, h[i].value);
+					if ((rc != NGX_OK) && conf->block) {
+						return NGX_HTTP_BAD_REQUEST;
+					}
 				} else {
 					/* TODO: support for other headers */
 					if (conf->log_uninspected) {