Objective: To assess the value of [F-18]fluoro-2-deoxy-D-glucose positron emission tomography ((18)FDG-PET) in defining aggressive cartilage neoplasms, particularly those with problematic or borderline histologic, imaging and clinical characteristics. Design and patients: From 2000 to 2003, 29 cartilage lesions were studied with whole-body (18)FDG-PET scans (Siemens Ecat Exact, Knoxville, Tenn.). Analyses of data in 20 females and nine males, 11-85 years old, were based on maximum standard uptake values (SUVs) in regions of interest (ROIs) on axial 3.37 mm thick, 3x3 pixel images. A statistically significant maximum SUV cutoff of 2.0 was used to distinguish benign from malignant cartilage neoplasms and correlated with the postoperative histopathologic findings. Results: In 26 operated cases the overall sensitivity of whole-body (18)FDG-PET in separating benign and malignant lesions was 90.9% (10/11), specificity 100% (18/18) and accuracy 96.6%. Conclusions: Whole-body (18)FDG-PET is a valuable adjunct in identifying primary, recurrent and metastatic cartilage malignancies. It supplements classic histology and morphologic imaging with functional data which may facilitate management in individual cases.