Tungsten disulfide (WS2) is a type of anisotropic-layered compound and has broadband saturable absorption features as saturable absorbers (SAs). With WS2-based SAs, dark solitons in erbium-doped fiber (EDF) lasers are first obtained. For the generated dark solitons, the center wavelength is measured to be 1530 nm, and the repetition rateis about 116.5 MHz. A series of optical spectra is exhibited. The electrical signal-to-noise ratio is better than 94 dB. Results in this paper demonstrate that WS2-based SAs are the promising SAs for generating dark solitons in EDF lasers.