diff --git a/libwccl/CMakeLists.txt b/libwccl/CMakeLists.txt
index dae29550b6d000fb14ff1f3c788bba7c473136c2..5466587c9b661694529a0eff7f3faf5aef994edb 100644
--- a/libwccl/CMakeLists.txt
+++ b/libwccl/CMakeLists.txt
@@ -58,6 +58,7 @@ SET(libwccl_STAT_SRC
 	ops/functions/tset/getsymbols.cpp
 	ops/functions/tset/getsymbolsinrange.cpp
 	ops/match/actions/markmatch.cpp
+	ops/match/actions/unmarkmatch.cpp
 	ops/match/applyoperator.cpp
 	ops/match/conditions/conjconditions.cpp
 	ops/match/conditions/longest.cpp
diff --git a/libwccl/ops/match/actions/unmarkmatch.cpp b/libwccl/ops/match/actions/unmarkmatch.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..f1ac2a90b1c40002f1652911690a2fd0ff551062
--- /dev/null
+++ b/libwccl/ops/match/actions/unmarkmatch.cpp
@@ -0,0 +1,52 @@
+#include <libwccl/values/match.h>
+#include <libwccl/ops/match/actions/unmarkmatch.h>
+#include <libcorpus2/ann/annotatedsentence.h>
+
+#include <sstream>
+
+namespace Wccl {
+
+void UnmarkMatch::execute(const ActionExecContext& context) const
+{
+	SentenceContext& sc = context.sentence_context();
+	boost::shared_ptr<Corpus2::AnnotatedSentence> as;
+	as = boost::dynamic_pointer_cast<Corpus2::AnnotatedSentence>(sc.get_sentence_ptr());
+	if (!as) {
+		throw InvalidArgument("context", "Operator needs an annotated sentence.");
+	}
+	if (!as->has_channel(chan_name_)) {
+		throw InvalidArgument("context", "Sentence does not have annotation channel \"" + chan_name_ + "\".");
+	}
+
+	int abs_pos = match_->apply(context)->first_token(as).get_value();
+	if(sc.is_outside(abs_pos)) {
+		throw WcclError("Received starting match that points outside sentence.");
+	}
+
+	Corpus2::AnnotationChannel& channel = as->get_channel(chan_name_);
+
+	int segment_idx = channel.get_segment_at(abs_pos);
+	if (segment_idx == 0) {
+		throw WcclError("No annotation \"" + chan_name_ + "\" to delete at the specified position.");
+	}
+
+	for (int i = 0; i < channel.size(); ++i) {
+		if (channel.segments()[i] == segment_idx) {
+			channel.set_segment_at(i, 0);
+		}
+	}
+}
+
+std::string UnmarkMatch::to_string(const Corpus2::Tagset& tagset) const
+{
+	std::ostringstream os;
+	os << name() << "(" << match_->to_string(tagset) << ", \"" << chan_name_ << "\")";
+	return os.str();
+}
+
+std::ostream& UnmarkMatch::write_to(std::ostream& os) const
+{
+	return os << name() << "(" << *match_ << ", \"" << chan_name_ << "\")";
+}
+
+} /* end ns Wccl */
diff --git a/libwccl/ops/match/actions/unmarkmatch.h b/libwccl/ops/match/actions/unmarkmatch.h
new file mode 100644
index 0000000000000000000000000000000000000000..b0cfd31e7bace0dbc916f6ab0116ed15ea2f5cfd
--- /dev/null
+++ b/libwccl/ops/match/actions/unmarkmatch.h
@@ -0,0 +1,58 @@
+#ifndef LIBWCCL_OPS_MATCH_ACTIONS_UNMARKMATCH_H
+#define LIBWCCL_OPS_MATCH_ACTIONS_UNMARKMATCH_H
+
+#include <libwccl/ops/match/matchaction.h>
+#include <libwccl/ops/function.h>
+
+namespace Wccl {
+
+/**
+ * Action to unmark (delete) an annotation passing through a first
+ * token of a Match.
+ */
+class UnmarkMatch : public MatchAction
+{
+public:
+	UnmarkMatch(
+			const boost::shared_ptr<Function<Match> >& match,
+			const std::string& annotation_name)
+		: match_(match_),
+		  chan_name_(annotation_name)
+	{
+		BOOST_ASSERT(match_);
+		BOOST_ASSERT(!chan_name_.empty());
+	}
+
+	/**
+	 * @returns Name of the action.
+	 */
+	std::string name() const {
+		return "unmark";
+	}
+
+	/**
+	 * Executes the action for the given execution context.
+	 */
+	void execute(const ActionExecContext& context) const;
+
+	/**
+	 * @returns String representation of the expression.
+	 */
+	std::string to_string(const Corpus2::Tagset& tagset) const;
+
+protected:
+	/**
+	 * Writes string representation of the MatchAction to
+	 * an output stream.
+	 * @returns Stream written to.
+	 * @note May be incomplete and/or containt internal info.
+	 */
+	virtual std::ostream& write_to(std::ostream& ostream) const;
+private:
+	const boost::shared_ptr<Function<Match> >& match_;
+	const std::string chan_name_;
+};
+
+} /* end ns Wccl */
+
+#endif // LIBWCCL_OPS_MATCH_ACTIONS_UNMARKMATCH_H
diff --git a/libwccl/parser/grammar.g b/libwccl/parser/grammar.g
index 9bea7459323dd907b6dd87c11b3c0ec026a1e118..3e553affe1fa62daaa202e3996b7c17469c53724 100644
--- a/libwccl/parser/grammar.g
+++ b/libwccl/parser/grammar.g
@@ -79,6 +79,7 @@ header {
 	#include <libwccl/ops/match/conditions/repeatedmatch.h>
 	#include <libwccl/ops/match/conditions/conjconditions.h>
 	#include <libwccl/ops/match/actions/markmatch.h>
+	#include <libwccl/ops/match/actions/unmarkmatch.h>
 
 	// Unicode String
 	#include <unicode/uniset.h>
@@ -1981,11 +1982,22 @@ match_mark_action
 ;
 
 // Match unmark action
-// Returns ???
+// Returns boost::shared_ptr<UnmarkMatch>
 match_unmark_action
 	[const Corpus2::Tagset& tagset, Variables& vars]
-	returns [boost::shared_ptr<MatchAction> m_act]
-	: "unmark" LPAREN /* TODO */ RPAREN
+	returns [boost::shared_ptr<UnmarkMatch> m_act]
+{
+	boost::shared_ptr<Function<Match> > match_at;
+}
+	: "unmark" LPAREN
+				match_at = match_fit[tagset, vars] COMMA
+				annotation_name : STRING
+			RPAREN {
+				m_act.reset(
+					new UnmarkMatch(
+							match_at,
+							((antlr::Token*)annotation_name)->getText()));
+			}
 ;
 
 // Match action separated by comma