Background: Morbus Ollier is characterized by the presence of multiple enchondromas, i.e. benign intraosseous cartilaginous lesions. Although their manifestation in the limb bones is well described, only few cases with ENT involvement, primarily arising from the skull, have been reported. The malignant transformation toward slowly growing low-grade chondrosarcomas is the most severe form of progression. Methods: We report a unique case of a 54-year-old Ollier disease patient with an extensive nasal enchondroma apparently eroding the middle nasal concha and expanding to the lateral nasal wall that raised suspicion of malignant transformation. Results: Radiological and histological features of enchondromas can be controversial and appear to have limited sensitivity to exclude low-grade malignancy. The clinical symptoms play a decisive role in differentiation between enchondromas and low-grade chondrosarcomas. Conclusion: Surgery remains the only effective solution in removing an enchondroma and preventing the tendency toward malignant transformation. Head Neck, 2014.