In the past the fixation procedures employed in the immunohistostaining of paraffin-embedded tissues with anti-myc protein antibodies were unsatisfactory since they permitted the leakage of the protein from its normal nuclear localization in the cell. In the studies described here 3 different fixation methods were compared and it was shown that only one, the AMeX method, was suitable for studying c-myc expression in bone marrow biopsies.