Twelve arene and cyclopentadienyl ruthenium(II) dithiocarbamate complexes have been prepared and characterized by spectroscopic methods. The structures of 3a and 3c have been determined by X-ray crystallography. Their in vitro antitumor activities were evaluated by MTT method against four tumor cells (SKOV-3, HepG-2, A549, as well as PC12) and two murine cells (RAW246.7 and L6). Notably, the results in vitro indicated that the arene ruthenium(II) complex 3e (N-methyl piperazine) displayed the highest activity and selectivity towards cancer HepG-2 cells.