Research has been conducted on the relationship between postnatal mortality from meningococcal infections and age, using data from the US during the period 1950-1991. The logarithm of mortality caused by meningococcal infections fell linearly with the logarithm of age, during the interval of 1-30 years for men and women in the US. The slope of this straight line is equal to -1. The mortality from meningococcal infections is inversely proportional to the age in the US. The risk of death at age 2 is one half of the risk at age 1, at age 3 it is one third of the risk of death at age 1, etc. up to the age of 30 in the US. The same decline was observed for the risk of death from congenital anomalies and pneumonia.