This study investigates whether the proliferative activity of giant cell tumour of tendon sheath is related to its recurrence rate and local aggressiveness. The clinicopathological and immunohistochemical features of 30 localized giant cell tumours of tendon sheath were studied and the influence of the MIB-1 staining index on recurrence, tumour extent around the phalanx and involvement of the bone were evaluated. No significant difference in the MIB-1 staining index was found between the lesions which recurred and those which did not. Also there was no significant association between local aggressiveness and the MIB-1 staining index. These results suggest that the proliferative activity of localized giant cell tumour of tendon sheath is not related to its high recurrence rate and local aggressiveness.