The detection of micrometastases in patients with operable non-small cell lung carcinoma (NSCLC) could have a considerable influence on the choice of a proper treatment.The aim of the study was to evaluate the usefulness of microscopic examination and immunohistochemistry for the detection of micrometastases or single malignant cells in the bone marrow of patients undergoing surgery for NSCLC, as their late survival and recurrence-free time is dependent on immunohistochemical markers of cancer metastases in the bone marrow.Material and methods. Thirty-five patients were included in the study. Their age range was from 47 to 78 years old. Bone marrow was obtained from a rib during surgery for lung cancer. Both a resected tumour and bone marrow sample were tested for the presence of cytokeratins AE1/AE3, CAM 5.2, CK-7, and CK-18 and other indicators such as CD31 and CD34. The mean time of observation was 871.6 days.Results. Microscopic examination detected no malignant cells or micrometastases in the bone marrow in the analyzed group. Cytokeratin CAM 5.2 was detected in 33 cases (94.23%) in a lung tumour and in 21 cases (60%) in the bone marrow. Statistical analysis (chi2 NW), showed a statistically significant relationship between the presence of CAM 5.2 expression in a tumour and in the bone marrow. In all analysed cases, the expression of cytokeratin AE1/AE2 was found in a tumour, but was not detected in any bone marrow sample. Cytokeratin CK-7 and CK-18 were present in a tumour in 20 (57.14%) and 23 (65.71%) patients, respectively. In the bone marrow, the expression of cytokeratin CK-7 was found in one case (2.86%), and CK-18 was not found in any patients. Thirteen (37.14%) patients died during follow-up. Local recurrence was diagnosed in three patients (8.57%) and distant metastases in 15 patients (42.86%). Mean recurrence-free time was 687.7 days.Conclusions. On the basis of immunohistological tests, it was shown that a significant correlation existed between the presence of cytokeratin CAM 5.2 expression in a tumour and in the bone marrow. Its presence in the bone marrow was a good predictive factor for recurrence-free time. Mortality and the frequency of locoregional recurrence and distant metastases depend on pathological lung cancer staging.