Combined exposure to chromium, nickel and cobalt occurs in many jobs : one of them is the Dental laboratory technicians who are exposed to these metal alloys during casting, finishing & polishing of dental prosthesis.In Our study we measured serum chromium, nickel and cobalt in dental technicians and it was higher than controls.Chromosomal aberrations in lymphocytes of dental technicians using bleomycin induction of breakage culture were also higher than controls indicating cytogeneitic toxicity of these metals.