In Turkish literature there are very few studies regarding multiple primary malignancies (MPM). The aim of this study was to analyze the synchronous and the metachronous malignancies that occurred with a hematologic malignancy. All the patients with a hematologic malignancy were enrolled in this cross-sectional, definitive retrospective study. Data were obtained from the medial records. Patients characteristics including demographic features, treatment protocols and overall survival (OS) were recorded. Among 663 patients with a hematologic malignancy, there were 26 patients with MPMs (3.9%). Synchronous malignancies constitute 0.9% and metachronous malignancies were present in 3%. In men diffuse large B-cell lymphoma (DLBCL) and non-small cell lung carcinoma (NSCLC) and in women breast and acute myeloid leukemia were the most common primary and secondary MPMs respectively. The mean cumulative OS of all patients with MPMs was 246.3±33.4 months and the 5 years-OS was 91.3%. In synchronous MPMs the most frequent concomitant tumors were DLBCL and NSCLC. In metachronous tumors the median time interval between first and second malignancies was 69.5 months (range: 31-312). In four patients there were three MPMs. After radiotherapy three patients developed breast, thyroid and skin cancers and in one patient who received radioiodine for the treatment of thyroid carcinoma, DLBCL had developed. The chemotherapeutic agents applied for the primary malignancies consisted of alkylating agents, antimetabolites, anthracyclines, topoisomerase II inhibitors, monoclonal antibodies and mitotic inhibitors. In 75% of the patients with DLBCL who had received R-CHOP chemotherapy regimen, NSCLC had developed during the follow-up period. In conclusion secondary malignancies with hematologic malignancies are not rare and the clinicians should keep the possibility of secondary malignancies in mind and be suspicious during diagnostic evaluations. Warning with regard to the risk of development of secondary malignancies due to the primary treatment should be given to any patient with a hematologic malignancy. [Med-Science 2020; 9(1.000): 94-9]