Overexpression of the olfactomedin 4 (OLFM4GW112,/hGC−1) gene was recently reported to inhibit various apoptotic pathways and promote proliferation of cancer cells, suggesting that OLFM4 might serve as a diagnostic marker for human cancers. Therefore, we examined cancer-specific OLFM4 overexpression. OLFM4 mRNA was highly expressed in cancerous tissues obtained from the colon, breast and lung. Positivity for OLFM4 mRNA, defined as the mean + 2 SD in non-cancerous colon and breast tissues, was observed in 68 and 50% of the studied colon and breast cancer tissues. OLFM4 mRNA expression was not detected in non-cancerous lung tissues but was evident in 62% of the lung cancer tissues. On comparing paired samples, the expression of OLFM4 mRNA was observed to be elevated in 90, 69 and 85% of colon, breast and lung cancer tissues, respectively. OLFM4 mRNA expression was observed even in the early stages of each cancer type. The expression of OLFM4 mRNA did not correlate with that of the antiapoptotic molecule survivin, indicating that it can be used independently in cancer diagnosis. Combining OLFM4 and survivin resulted in higher positivity. Thus, OLFM4 mRNA might be a useful tool to support the diagnosis of cancer, irrespective of the clinical stages.