To investigate whether the administration of fresh-frozen plasma to patients with systemic meningococcal disease is associated with an increased mortality rate compared with the administration of plasma substitutes.Seventeen-year case-control study.Intensive care units and departments of internal medicine and pediatrics of one university hospital and one local hospital.A total of 336 patients with culture-proven meningococcemia or symptoms characteristic of meningococcemia who were admitted to two hospitals in northern Norway between 1974 and 1991.High-risk patients were selected on the basis of two different scoring systems (Niklasson's score and clinical score) and classified according to the type of intravenous fluid regimen (fresh-frozen plasma, blood, or colloids). For comparison between groups, analysis of variance and chi-square tests were used. Assessments of adjusted effects on mortality rate were done by multiple logistic regression. Administration of blood or plasma was significantly associated with a fatal course, both in the total patient population (p < .01) and in the high-risk group (p = .02), while using colloids alone was negatively associated with death, although not reaching statistical significance. A significantly lower mortality rate was found in one of the hospitals where colloids were used instead of plasma or blood in the last part of the period studied (p < .05).The results support our hypothesis that the use of fresh-frozen plasma may negatively influence outcome in systemic meningococcal disease.