We included 685 consecutive previously healthy well appearing infants younger than 3 months with fever without known source admitted to an Emergency Department without routinely performing lumbar punctures (LP). LP was performed in 198 infants. Of these, 36 (18.1%) showed pleocytosis. Two infants less than 15 days were diagnosed with bacterial meningitis and 47 with aseptic meningitis (6.8%). LP was not performed in 487 infants. Of these, 69 were admitted to ward (46 had urinary tract infection) and 418 were discharged. In this group, we registered 38 unscheduled revisits to the Emergency Department (four aseptic meningitis). All infants did well. It is unnecessary to perform a LP routinely on infants over 1 month of age. The decision to perform the LP in previously healthy and well appearing infants with fever without known source attended by an experienced paediatric emergency physician can be individualized with no subsequent adverse outcomes. This approach may lead to under-diagnosing nonbacterial meningitis.