We describe eight cases of acute proptosis due to mantle cell lymphoma (MCL), among 26 consecutive MCL cases. The median time of onset was 29 months (range 0-102) from diagnosis. Two cases presented initially with orbital masses while five as sudden disease progression after multiple courses of chemotherapy. In each case, there was dramatic loss of vision and severe proptosis, which uniformly responded to radiotherapy and/or further chemotherapy. Unilateral blindness only occurred in two cases, with recurrent orbital relapse and repeated retinal irradiation and retro-orbital optic nerve involvement, respectively. The high incidence, as well as bilateral and recurrent nature, of orbital involvement suggested a homing mechanism of MCL to this site. Despite the absence of central nervous system involvement, most cases died of refractory disease. Apart from lymphomatous polyposis of the gut, MCL cells also show predilection to ocular presentation, and must be considered as a differential diagnosis to maltoma in the two anatomical sites.