Richter transformation (RT) refers to a transformational process of chronic lymphocytic leukemia (CLL) into a more aggressive form. CLL is considered an indolent lymphoma with no avidity to ¹⁸F-fluorodeoxyglucose positron emission tomography/computed tomography (¹⁸F-FDG PET/CT). RT transforms CLL into a diffuse large B-cell lymphoma, Hodgkin’s lymphoma, or prolymphocytic leukemia, and the lymphoid tissue becomes highly FDG avid. The main value of ¹⁸F-FDG PET/CT in CLL patients lies in its ability to exclude RT with high negative predictive value and identify sites of increased ¹⁸F-FDG uptake that is suitable for biopsy. In our retrospective analysis, we examined 12 patients suspected of RT, who were included in our study between November 2018 and December 2022. ¹⁸F-FDG PET/CT was considered for patients with enlarged lymph node, fever, and elevated lactate dehydrogenase levels. A cutoff standardized uptake value (SUVmax) = 5 was chosen empirically based on our institutional practice. Extranodal disease was suspected if abnormal ¹⁸F-FDG uptake was observed in the liver, spleen, bone marrow, or another organ. In this study, the specificity of ¹⁸F-FDG PET/CT was 44.5%, with positive and negative predictive values of 37.5% and 100%, respectively. Frequencies of cases with increased uptake of ¹⁸F-FDG in the “only nodal sites” and “nodal and extranodal sites,” relative to positive biopsies, were 20% and 66%, respectively.