In this paper, antineoplastic activities of protein-conjugated silver sulfide nano-crystals with different shapes were described in detail. Transmission electron microscope analysis demonstrated that stable and well-disperse protein-conjugated silver sulfide nano-particles, nano-rods, and nano-wires could be prepared by aqueous chemistry method. The Fourier transform infrared spectrograph analysis indicated the strong coordination between silver sulfide surfaces and –OH and –NH groups in bovine serum albumin. The antineoplastic activities of protein-conjugated silver sulfide nano-crystals were examined by cell viability analysis, optical and electron microscopy methods. The results showed that nano-particles, nano-rods and nano-wires could inhibit the proliferations of human hepatocellular carcinoma Bel-7402 cells and C6 glioma cells, and the activities were size-dependent.