A new, atomic absorption spectrophotometric method for serum iron and iron-binding capacity is described, which utilizes 20% (w/v) TCA plus heating at 90° for 15 min. This procedure liberates the ferric iron; precipitates the protein, facilitating removal by centrifugation; and avoids significant interferences by contaminating hemoglobin iron. The method is highly specific, accurate, and has the additional feature of requiring less time than most colorimetric or atomic absorption methods employing chelation and extraction.