['To investigate whether the expression level of valosin-containing protein (VCP) is correlated with the prognosis of primary orbital mucosa-associated lymphoid tissue (MALT) lymphoma.', 'VCP expression in 58 samples from primary orbital MALT lymphoma patients was determined by immunohistochemisty using monoclonal antibodies. Correlations between VCP expression level and prognosis were clarified by statistical analysis.', 'It was found that the percentage of VCP positive cells in samples of primary orbital MALT lymphoma ranged from 32% to 95%. The samples were divided into two groups (level 1 and level 2) according to the median value (45%) of the percentage of VCP positive cells. It was found that the expression level of VCP was significantly correlated with recurrence (P=0.003) and tumor size (P=0.008). At the same time, the 5-year disease-free and overall survival rate of patients of level 1 was significantly better than that of level 2 (P=0.001; P=0.032). There was no observed correlation between the expression level of VCP and other clinical features.'] Is expression level of valosin containing protein associated with prognosis of primary orbital MALT lymphoma?