The analytical in vivo chromium ion was searched for using a voltammetric hollow-fiber dialysis sensor via square wave stripping voltammetry (SW), cyclic voltammetry (CV), and chronoamperometry. Under optimum parameters, the analytical results indicated linear working ranges of 50~400 mg/l CV and $10{sim}80;{mu}g/l$ SW within a 30-sec accumulation time. The analytical detection limit (S/N) was $6.0;{mu}g/l$. The developed method can be applied to in vivo tissues and in ex vivo toxicity assay, as well as to other materials that require chromium analysis.