Objective to describe fathers' experiences during childbirth. Design qualitative method with phenomenological lifeworld approach. A re-enactment interview method, with open-ended questions analysed with a phenomenological method, was used. Participants and setting 10 first-time fathers from two hospitals were interviewed four to six weeks after childbirth in Southwest Sweden during the autumn of 2008. Findings the essential meaning of first-time fathers' lived experience of childbirth was described as an interwoven process pendulating between euphoria and agony. The four themes constituting the essence was: ‘a process into the unknown’, ‘a mutually shared experience’, ‘to guard and support the woman’ and ‘in an exposed position with hidden strong emotions’. Key conclusions childbirth was experienced as a mutually shared process for the couple. The fathers' high involvement in childbirth, in cooperation with the midwife, and being engaged in support and care for his partner in her suffering is fulfilling for both partners, although the experience of the woman's pain, fear of the unknown and the gendered preconceptions of masculine hegemony can be difficult to bear for the father-to-be. Implications for practice in order to maintain and strengthen childbirth as a mutually shared experience for the couple, the father needs to be recognised and supported as a parent-to-be. Midwives have to acknowledge fathers as valued participants and support their significant position.