This experiment was performed to study the sequential accumulation of mercury in selected tissues of gold fish (Carassius auratus) exposed to 2, 6, 30, 120 and 300 $mu$g Hg/1 as HgCl$_2$. In order to prepare treatment groups suitable for the present study, one control and five experimental groups, which were composed of I (2 $mu$g/l), II (6$mu$g/l), III (30$mu$g/l), IV (120$mu$g/l), V (300 $mu$g/l), were used in 180 liter glass aquaria. The experiment was started by transfering 20 fish of average total length 140 $pm$ 20 mm to each of the six tanks and allowing the uptake to take place for 12 weeks period. Fish were killed after time periods of 1, 2, 4, 8, and 12 weeks, and samples were disected by five parts gill, kidney liver, muscle and egg. The summarized results were as follows: 1. In control group, low concentrations of mercury(range 0.01-0.11 $mu$g/g)were determined in the all selected tissues. 2. In experimental group, the average levels of mercury residues in the gill, kidney, liver muscle and egg were 3.61-189.54 $mu$g/g, 13.91-182.58 $mu$g/g, 8.56-66.49 $mu$g/g, 0.30-20.33 $mu$g/g, and 1.63-23.76$mu$g/g, respectively. 3. The mercury residues in selected tissues of the experimental group were generally 230-9100 times higher than those of the control group. 4. The amounts of methylmercury per total mercury in the muscle after 12 weeks were 0.10/0.30 $mu$g/g(33.33%) in the I group, 0.14/1.18$mu$g/g(11.86%) in the II group, 0.25/5.76 $mu$g/g(4.34%) in the III group, 0.39/11.48$mu$g/g(3.40%) in the IV group and 0.40/20.33 $mu$g/g(1.97%) in the V group.