Purpose: There is no data in the literature concerning the utility of 2-[18F]fluoro-2-deoxy-d-glucose positron emission tomography (FDG-PET) in chronic lymphocytic leukaemia (CLL), except for the diagnosis of Richter's transformations. The purpose of this study was to assess the potential role of FDG-PET in CLL stages A and B. Materials and methods: Thirty-five patients (61 ± 9 years; 11 women, 24 men; 8B and 27A) have benefited of a FDG-PET scan at baseline, for example, before an eventual treatment. FDG-PET scans were analyzed visually and the maximum values of the Standardised Uptake Value (SUVmax) were measured in the main lymph nodes areas. The ability of FDG-PET to differentiate stages A and B patients was evaluated by Student's tests and Receiver Operating Characteristics (ROC) analysis. Results: All patients with a normal FDG-PET (n = 18) were stages A. The remaining 17 patients (9A and 8B) showed hypermetabolisms in nodal areas above (n = 17) and below (n = 9) the diaphragm, and no visceral involvement. The lymph nodes hypermetabolisms were always bilateral, and of low intensity (≤ mediastinum; 9A), or of higher intensity (≥ liver, 8B). The SUVmax of stage B (n = 8) were significantly higher than those of the 27 stages A, in all lymph nodes areas except in mediastinum. The highest intensity of FDG uptake was observed in axillary area in stages B patients (SUVmax = 2.74 ± 1.03). An axillary SUVmax of 1.33 is the most suitable value for the discrimination between stages A and B patients (ROC; AUC = 0.968; sensitivity 1.00; specificity 0.91). Conclusion: Lymph nodes hypermetabolisms are constant in the B stage, and more intense than in stage A. These anomalies are always bilateral, unlike what is observed in Richter's transformation. The intensity of axillary lymph nodes FDG uptake can distinguish CLL stages A and B.