Surveillance of meningococcal disease is vital if we are to respond to a changing burden of disease, but current sources of routine data suggest different trends. A scheme for enhanced surveillance of meningococcal disease began in the West Midlands in January 1996 using several data sources, including case reporting from consultants in communicable disease control, data from the PHLS Meningococcal Reference Unit, and monitoring of statutory notifications and laboratory reports. One thousand two hundred and twenty-eight cases of probable meningococcal infection were identified in three years (1996-1998), 594 of which were laboratory confirmed. Routine data for the same period yielded smaller totals--920 notifications and 412 laboratory reports--suggesting that these sources underestimate incidence by 25% to 30%. Diagnosis by polymerase chain reaction became increasingly important, and accounted for 38% of confirmed cases in 1998. A significant excess of male cases was observed (p < 0.01), most obvious in children under 5 years of age. There was no increase in N. meningitidis C2a strains, which had been identified as a threat nationally. A national system of enhanced surveillance has now been set up to inform programmes that aim to reduce the burden of meningococcal infection.