Background: Patterned breathing is one way that women cope with labor. Fatigue is a frequently reported symptom over which women and caregivers have little control. The purpose of this study was to examine the relationship between the use of patterned breathing, a traditional intervention, and the level of fatigue reported during the first stage of labor. Method: A secondary analysis was conducted on a subset (n = 56) of a prospective longitudinal study of fatigue during the intrapartum period. The sample comprised primiparous women in labor whose fatigue was measured every two hours for six hours after admission. At each data point the investigator evaluated the method of breathing that participants used. Results: During the latent phase of labor, women using patterned breathing exhibited significantly more fatigue. In the active phase, differences between groups were not significant. Controlling for age, education, and marital status of participants did not change the results. Conclusions: It is appropriate for nurses, midwives, physicians, and doulas to encourage the use of patterned breathing as an intervention in active labor; however, patterned breathing may increase the mother's fatigue level if begun too early. (BIRTH 25:4 December 1998).