KAI1/CD82 is a metastasis suppressor gene located on human chromosome 11p11.2. It is a member of the structurally distinct family of cell surface glycoprotein, transmembrane 4-protein superfamily.1 KAI1 was initially isolated as a gene that suppressed metastasis of rat prostate tumour cells.2 KAI1 is downregulated in several types of human malignancies.3–5 The purpose of this study was to investigate the expression of KAI1 in retinoblastoma and to correlate clinicopathologically. There were 30 archival specimens of retinoblastomas from 2000 to 2002. There were 12 tumours with no invasion of choroid, or optic nerve and 18 tumours with invasion of choroid/optic nerve, and one tumour which had metastasised to the submandibular region. There were six well differentiated tumours, six moderately differentiated tumours, and 18 poorly differentiated tumours (table 1). Immunohistochemical staining was performed using a sensitive labelled streptavidin biotin (LSAB kit, Dako) on tumours using monoclonal …