To determine whether lumbar puncture is necessary in the evaluation of neonates with risk for infection or suspected sepsis in the first 72 hours of life, we reviewed the laboratory and medical records of 506 infants who had lumbar punctures between January 1988 and December 1990. Neonates < 72 hours of age accounted for 52% of all lumbar punctures, but no case of meningitis. This led to a policy shift from routinely performing lumbar punctures to reserving them for infants with signs of severe sepsis (i.e. lethargy, hypothermia, hypotonia, poor perfusion or apnoea), specific neurological signs or clinical deterioration. This new policy was monitored prospectively from July 1991 to December 1993. Three times fewer procedures were performed in neonates < 72 hours, and there was no diagnosed or missed case of meningitis. Given that meningitis is rare within the first 72 hours of life and the yield of lumbar puncture virtually zero, we recommend that lumbar punctures be reserved for selected infants.