The expression of CD300LG-γ at mRNA and protein level was detected by semiquantitative reverse transcription-polymerase chain reaction (PCR), quantitative real-time PCR, and western blot, and compared by t-test analysis. The results of semiquantitative reverse transcription-PCR showed that the mRNA expression of CD300LG-γ was significantly lower in pulmonary carcinoma tissues, compared to tumor-adjacent tissues. The results of quantitative real-time PCR confirmed this finding. The mRNA level of CD300LG-γ in pulmonary carcinoma tissues compared with tumor-adjacent tissues was 0.436-fold in a median. The results of western blot indicated that CD300LG-γ protein was expressed in both pulmonary carcinoma and tumor-adjacent tissues, and the expression level was significantly lower in pulmonary carcinoma tissues compared with tumor-adjacent tissues. Both mRNA and protein levels of CD300LG-γ in pulmonary carcinoma tissues were significantly lower than that in tumor-adjacent tissues, which might lead to inhibition of killing function of immunocytes, resulting in immune escape of lung cancer cells.