Abstract.In 1958–1974 altogether 46 cases of bacteriologically verified infection of Listeria monocytogenes were diagnosed during pregnancy and the neonatal period. Eight pregnancies resulted in abortion and three in stillbirth. Thirty‐seven children were born alive, 17 of whom died, all but one within a few days. These children were divided into three groups according to their age at the onset of illness: 22 cases with “Early disease” (≤2 days), four cases with “Intermediate disease” (3–5 days) and eight cases with “Late disease” (≤6 days). Three children were apparently healthy. Septicemia or “Granulomatosis infantiseptica” dominated in “Early disease” and claimed as many as 13 deaths. In “Late disease” all the children had meningo‐encephalitis, and only one of them died. The symptoms were typical of purulent meningitis. The group of “Intermediate disease” consisted of overlapping cases of the other two groups. Ampicillin alone or combined with gentamicin seemed to be the drug of choice in the therapy of neonatal listeriosis. Of the surviving children, two were seriously damaged and two had moderate injuries. Fifteen children are apparently healthy. In cases where pregnancy terminated in abortions, stillborns or children with “Early disease”, the mothers often showed signs of infection. The mothers of the children with “Late disease” were apparently healthy. These children were infected from other sources, some of them nosocomially. If listeriosis is diagnosed during pregnan