A simple method was developed for the determination of cadmium (Cd) and lead (Pb) in milk serum prepared by spontaneous souring, using graphite furnace atomic absorption spectrophotometry. Samples of raw milk were collected from the bulk holding tanks of thirty-six dairy farms in twelve localities in Izmit. The samples were kept at room temperature (25 degrees C) for 48 h in order to allow the pH to decrease below 4.6, and the casein and fat to precipitate. Milk serum was filtered and directly injected into a graphite tube. The standard addition method was employed, and 0.1% phosphoric acid was used as the matrix modifier. The mean recoveries from three added concentrations were 91.4% for Cd and 95.8% for Pb. Cadmium and Pb concentrations found in the reference standard milk powder using this method were close to the certified values. The mean Cd contents obtained from thirty-six samples were 0.257 mu g L-1, ranging from 0.180 to 0.398 mu g L-1. The mean Pb contents found were 6.83 mu g L-1, ranging from 5.32 to 9.94 mu g L-1.