We investigated the effectiveness of a loop-mediated isothermal amplification (LAMP) assay to screen meat samples to detect enterohemorrhagic Escherichia coli serovar O157 and O26. Ninety beef rumen samples were cultured in mEC broth at 37°C and noboviocin-containing mEC broth (N-mEC) at 42°C, and then assayed by LAMP reactions. Twenty-eight mEC culture samples were positive by LAMP assay but no samples were positive for EHEC O157 or O26 by the immuno-magnetic separation (IMS) method. Among N-mEC culture samples, 17 samples were positive by LAMP assay and EHEC O157 was isolated from one sample by IMS method, but no sample was positive for EHEC O26 by IMS method. The rate of concordance for negative results between LAMP assay and IMS method (true negative fraction) was 0.8202 for EHEC O157 and 0.8111 for EHEC O26 by N-mEC culturing. By mEC culturing, true negative fraction was 0.6889 for both EHEC O157 and O26. The effectiveness of LAMP assay for screening was also confirmed using retailed meat samples. Four out of 100 retailed meat samples had positive LAMP reactions, and no EHEC O157 or O26 was isolated from the positive samples. For retailed meat samples, true negative fraction was 0.98 for EHEC O157 or O26. These results suggested that LAMP assay was effective for screening meat samples for EHEC O157 and O26.