The problems with setting up breastfeeding are common and are associated with an increased risk of weaning. The main reasons brought up by the mothers who adopted early weaning were fatigue and suboptimal infant breastfeeding behavior (SIBB). The goal of this study is to describe the fatigue levels of breastfeeding women who gave birth to healthy full-term babies in a hospital setting, and to examine the relationship between these fatigue levels and SIBB. This descriptive correlational and cross-sectional study was conducted with breastfeeding women who gave birth to healthy, full term, single babies at the CHU in Moncton between June and September 2013. The Fatigue Continuum Form and the Infant Breastfeeding Assessment Tool were used to measure fatigue and SIBB respectively. Analysis was carried out using Spearman’s correlation coefficient (r) and bivariate associations were measured using the chi-square test (χ2). Sixty-four mother-child dyads were included in this study. 64.1% of mothers experienced moderate fatigue. Maternal fatigue was associated with parity (p=0,003), the mothers’ level of education (p=0,043), the child’s birth weight (p=0,035), the delay before introducing the breast (p=0,001), and the frequency of feedings on D0 (p=0,037). The prevalence of SIBB was 57.8% on day 0 (D0) and 25% on day 1 (D1). SIBB is associated with a frequency of less than eight feeds in the first twenty-four hours (D0 (p=0,001) and D1(p=0,003)), primiparity (D1) (p=0,046), nipple types (D1) (p=0,010), previous breastfeeding experience (D1) (p=0,046), skin on skin contact in the delivery room (D1) (p=0,041), and the amount of time before the baby’s first introduction to the breast (D1) (p=0,027). À significant correlation was noted between maternal fatigue and SIBB on D0 (r=0,196; p=0,029) and between SIBB on D0 and on D1 (r=0,661; p<0.001). A special supervision of mother-child dyads that are at risk is necessary in order to benefit from extra support during hospital stays and following their discharge from the hospital.