Suspected infanticide cases came to the attention of the authorities on a weekly basis in the second half of nineteenth-century Ireland. Irish court documents, prison records and newspapers examined as part of this research referred to 4,643 individual cases of attempted infanticide, infant murder and concealment of birth. Yet only 135 putative fathers of illegitimate babies were referred to either by name, place of residence, occupation, marital status or class position. This article focuses on these 135 men. We can deduce from their absence from the sources that many of the men named in the records played little role in the lives of the women subsequent to the pregnancies. Other men mentioned in the records denied that they had fathered the dead infants at a time when paternity could not be verified. The evidence indicates, however, that some putative fathers actively responded to the pregnancies or births of their offspring. This article illustrates that some fathers sought abortions to hide the evidence of their illicit relationships prior to the births, directed acts of infanticide or concealment of birth, or attempted to dispose of the dead bodies of the infants. An examination of the putative fathers who were suspected of aiding with the offence reveals much about attitudes to "illegitimate" sexuality in post-Famine Ireland. As this article illustrates, when there was direct evidence that they were involved in a case of infanticide, putative fathers were punished by the nineteenth-century Irish courts.