Cobra snakebites are one of the most frequent occurrences among the poisonous snakebites. The correlation between the serum concentrations of cobra venom in the victims with the severity of systemic and local symptoms after envenoming is still awaited for investigation. In this paper, we have developed an enzyme-linked immunosorbent assay (ELISA) to detect Taiwan cobra venom existed in the serum of the cobra snakebite victims. This established technique allowed us to detect as low as 1 ng/ml. Totally, 31 serum samples of 27 recognized and suspected cobra snakebite patients were analyzed by the developed ELISA technique. The highest venom level detected was 1270 ng/ml in a case 2 h after being envenomed. We found that the serum concentrations of the venom in the bitten patients were well correlated with the severity of local tissue destruction. Venom levels might remain high 48 h after snakebite. Two or more vials of specific antivenom administered soon after snakebite were effective in neutralizing the circulating venom as revealed by ELISA. Higher doses of antivenom may be indicated in cases of cobra venom-induced local tissue destruction. In conclusion, these results indicate that venom detection in snakebite victims is valuable in diagnosis and severity assessment of Taiwan cobra snakebite.