Based on 92537 blood samples received from 7365 patients with a request for a meningococcal antibody test (MAT) during a 10-year period (1986–1995), the usefulness of the test in the diagnosis of meningococcal disease was assessed. Of 635 patients with culture-confirmed meningococcal disease, 88% were seronegative on admittance to hospital and 90% were seropositive 10–15 days after onset of disease. The humoral immune response in children <2 years of age was weaker than in older children and adults. Among 893 MAT-positive patients without culture-confirmed meningococcal disease, 261 (29%) had been notified as cases of meningococcal disease. Among 228 patients notified as serologically confirmed the MAT results were consistent with the clinical diagnosis in 86%. MAT is a reliable tool for establishing a diagnosis in patients with suspected meningococcal disease. Key factors facilitating appropriate interpretation of negative as well as positive test results were: time(s) of sampling(s) after onset of disease, age of the patient and clinical features.