OBJECTIVE: To investigate the relative validity of bioelectrical impedance analysis (BIA) in estimating fat mass (FM) and fat free mass (FFM) with dual-energy X-ray absorptiometry (DXA) as reference method in women with overweight and obesity 2 weeks and 6 months postpartum (pp). METHODS: Body composition of 94 women with overweight and obesity was assessed using Seca mBCA 515 and GE Healthcare Lunar iDXA. Agreement between the two methods for FM and FFM at 2 weeks and 6 months pp, as well as the changes in FM and FFM between the two timepoints, were tested using paired RESULTS: The mean (standard deviation [SD]) body mass index (BMI) at 2 weeks pp was 30.6 (2.6) kg/m CONCLUSIONS: At group level, BIA was a valid tool for assessment of FM and FFM in women with overweight and obesity at 2 weeks and 6 months pp when compared to DXA. We also consider it valid for following changes in FM and FFM over time when fluid distribution is stable.