Leukemoid reaction is defined as leucocytosis >50G/l. When it occurs in association with a malignancy, and infection or leukemia has been ruled out, it is termed as paraneoplastic leukemoid reaction. We report a case of a patient presented with fatigue, generalized weakness, and was incidentally noted to have a white blood cell count of 139G/l. Leukemia was ruled out by peripheral smear and flow cytometry. Computed tomography–guided biopsy of thickened omentum revealed poorly differentiated metastatic carcinoma. Leukemoid reaction is a diagnosis which must be evoked in front of any extreme hyperleukocytosis apart from associated infectious or hematological situations. This syndrome has an extremely pejorative prognostic value.