Multiple myeloma-related monoclonal gammopathy is a well-known cause of highly elevated serum protein [1]. However, other diseases inducing major polyclonal immunoglobulin production can be responsible for very high serum protein levels. The relative frequency of the causes of protidemia >100g/L has not been assessed. The purpose of the present study was to assess the etiological spectrum of protidemia >100g/L in unselected hospitalized patients of a tertiary care hospital.