Background: Exposure to perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS) have been associated with higher circulating concentrations of total cholesterol (TC) and low density lipoprotein cholesterol (LDL-C). ApoB is the primary apolipoprotein component of LDL-C, and acts as a ligand for LDL-C receptors in various cells throughout the body. Circulating concentrations of ApoB are considered to be a better indicator of heart disease risk than TC or LDL-C. Objectives: Explore associations of concentrations of PFOA and PFOS with serum ApoB in adults. Methods: We analyzed data from 2744, 20-80 years old participants in the 2005–2006 National Health and Nutrition Examination Survey (NHANES). Linear regression models were used to estimate adjusted predicted means of serum ApoB (in g/L) for quartiles of PFOA and PFOS (in ng/mL) to describe patterns of associations. Results: Adjusted predicted mean concentrations of serum ApoB did not appear to vary meaningfully with increasing concentrations of PFOA (Q1 1.11, Q2 1.02, Q3 1.01, Q4 1.02) or increasing concentrations of PFOS (Q1 1.06, Q2 1.05, Q3 1.07, Q4 0.99) in study participants. Conclusions: Exposure to PFOA or PFOS does not appear to alter Apo B concentrations in adults.