This study was performed to assess the recent trends in lead, mercury, and cadmium levels in the blood among Korean adult population. The geometric means and 95 % confidence intervals (CIs) of blood lead, mercury, and cadmium concentrations were calculated using the data of the subjects from the third (2005, n = 1997), fourth (2008, n = 2005; 2009, n = 1991), and fifth (2010, n = 1989; 2011, n = 2014) Korea National Health and Nutrition Examination Survey. Blood lead levels in 2005, 2008, 2009, 2010, and 2011 declined to 2.61 μg/dL (2.51-2.71), 2.32 μg/dL (2.27-2.37), 2.29 μg/dL (2.23-2.35), 2.09 μg/dL (2.04-2.13), and 1.99 μg/dL (1.94-2.05), respectively. Blood mercury levels were 4.19 μg/L (3.99-4.39), 4.73 μg/L (4.57-4.89), 4.25 μg/L (4.09-4.41), 3.64 μg/L (3.49-3.80), and 3.08 μg/L (2.95-3.22), respectively, which indicated an increase in 2008 compared with those in 2005, and a clear downward trend from 2008 to 2011. Blood cadmium levels were 1.52 μg/L (1.47-1.57), 0.93 μg/L (0.89-0.97), 0.94 μg/L (0.90-0.98), 0.89 μg/L (0.87-0.92), 0.86 μg/L (0.83-0.89), respectively, which indicated very high levels in 2005, but a downward trend since 2008. Although the lead, mercury, and cadmium levels in the blood of the Korean adult population are on the decline, they are still relatively high compared with those for the population of the USA, Canada, and Germany. Thus, continuous biological monitoring and measures to reduce these levels are needed in Korea.