Pathologic splenic rupture in non-Hodgkin's lymphoma (NHL) is a rare event, with 32 cases previously reported. Initial presentation of NHL with this complication is even rarer. We report such a case in an 80-year-old man with mantle cell lymphoma (MCL). It is notable that of the previously reported cases of pathologic rupture, three have occurred in MCL, suggesting that patients with this uncommon subtype of NHL may be particularly vulnerable to pathologic splenic rupture. Following splenectomy the patient's disease behaved in a high-grade fashion. Despite an initially encouraging response, his disease ran an aggressive course and he succumbed within four months. This case demonstrates the presentation of MCL with pathologic splenic rupture, as well as the potentially highly malignant behaviour of the disease.