The present study was undertaken to determine the aflatoxin M-1 (AFM(1)) levels in various cheese samples in Istanbul. A total of 363 samples of cheese, 131 samples of white cheese, 132 samples of processed cheese, 100 samples of kashar cheese brought to the Istanbul Military Food Control Laboratory were analysed from 2002 to 2004. The quantitative detection of AFM(1) levels in the samples was performed by competitive enzyme linked immunoassay (ELISA) method. AFM(1) levels in 283 (77.96%) of 363 cheese samples were found to be lower than 0.25 mu g/kg, determined as the maximum acceptable limit by the Turkish and International Standards and 80 (22.04%) of those were higher. The samples of unacceptable level rates were also quite different depending on the years. The highest rate (40.19%) was determined in 2002 and the rates in 2003 and 2004 were 15.39% and 13.49%, respectively. The results have indicated that high level of AFM(1) in cheese samples can provide a potential risk for consumer health, but the decreasing level of AFM(1) in the latest years may be evaluated as positive progress.