Chatkal State Nature Reserve is a reserve in the Tashkent Province of Uzbekistan comprising about 570 square kilometres of mountain steppes, mountain forests, alpine meadows, river valleys and floodplain forests. The state nature preserve was established here in 1947, and it was designated a UNESCO biosphere reserve in 1978. The most important river in this area is the Tereklisay, flowing from south to north across the nature reserve.