Physicians faced with a newborn infant with signs and symptoms of perinatal infection must consider a multitude of diseases, and may need to embark on a complex differential diagnosis. As stated by Alford in 1967, "neonatal diagnoses of infections acquired in utero, natally and postnatally, are inherently difficult." Twenty years later, this statement is still true. In this review, the diagnostic problems encountered in the evaluation of a suspected perinatal infection have been discussed, as have the complexities of the evaluation process for the original four TORCH agents, as well as for three additional agents. From our point of view, the usefulness of the TORCH acronym has been to focus attention on perinatal infections. Its main drawback has been the resultant overuse of TORCH titers ignoring the complexity of the diagnostic process. Ideally, the TORCH concept serves two functions. It continues to remind us of the multiplicity of pathogens that can cause perinatal infection, and it underscores the need for thorough diagnostic evaluation for these challenging infections. We believe that this is an appropriate expansion of the TORCH complex, and we anticipate that this expanded TORCH complex will continue to grow.