An osteoblastoma in a carpal bone is very rare and presents a problem of reconstruction after wide tumour excision. We report a case of recurrent osteoblastoma of the right hamate bone with involvement of the ulnar carpal bones and soft tissues that was successfully treated by en bloc resection, temporary interposition of bone cement and fixation with K-wires, followed by reconstruction with a free vascularized iliac crest flap, tailored to the exact size of the defect, in a second procedure. Rapid fusion was achieved and hand function preserved with no evidence of recurrence 3 years postoperatively.