This article analyzes the influence of the buyer-supplier relationship continuity on service performance. We used a survey with a sample of 53 companies that are users of international maritime transport belonging to two industries: Machinery and Food. The results related to Service Performance are similar to those found in past studies in industrial supply chains. The traditional performance criteria like delivery, dependability and cost clearly are influenced by the aspects related to the management of the relationship. This includes information exchange, trust and interaction between the parts.