The Sazliyka or Rakitnitsa (Bulgarian: Сазлийка, pronounced [sɐzˈlijkɐ]; also transliterated Sazlijka or Sazliika) is a river in southeastern Bulgaria, a left tributary of the Maritsa.

The river takes its source under the name Toplitsite at an altitude of 651 m some 1.5 km southwest of the summit of Ruya (812 m) in the Sredna Gora mountain range.

Downstream of the village of Starozagorski bani the river heads south-southwest and after receiving its tributary the Chatalka turns southeast.

Its drainage basin covers a territory of 3,239 km2 or 6.1% of the Maritsa's total and borders the drainage basins of the Omurovska reka, Tekirska reka, Martinka and Arpadere to the west and southwest, and the Tundzha to the north and east, all of them left tributaries of the Maritsa.

A 2009–2012 study identified 16 autochthonous fish species in the lower course of the Sazliyka: northern pike, common bleak, round-scaled barbel, Prussian carp, Eurasian carp, Vardar nase, Aegean gudgeon, Orpheus dace, European bitterling, common roach, Macedonian vimba, Struma spined lorch, wels catfish, European perch, zander and western tubenose goby.