Voltammetric analysis of mercury ions was developed using paste electrodes (PEs) with DNA and carbon nanotube mixed electrodes. The optimized analytical results of the cyclic voltammetry (CV) of the $1{sim}14ng;L^{-1}Hg(II)$ concentration and the square wave (SW) stripping voltammetry of the $1{sim}12ng;L^{-1}Hg(II)$ working range within an accumulation time of 400 seconds were obtained in 0.1 M $NH_4H_2PO_4$ electrolyte solutions of pH 4.0. For the relative standard deviations of the $1ng;L^{-1}Hg(II)$, which were observed at 0.078% (n = 15) at the optimum conditions, the low detection limit (S/N) was pegged at $0.2ng;L^{-1}(7.37{ imes}10^{-13}M)$ for Hg(II). The results can be applied to assays in biological fish kidneys and wastewater samples.