The purpose of this study was to examine the effect of three ventilation conditions (i.e., normal, regimented, and no-ventilation) on the reproducibility of bioimpedance scores in humans for the forearm and trunk segments. One hundred able-bodied North American men and women, from 18 to 71 years of age, volunteered as participants. The experimenters used a Xitron Bio-Impedance Analyzer System model 4200 instrument with Hydra software (Xitron Technologies, San Diego, California, USA) to collect bioimpedance data on extracellular fluid and intracellular fluid scores. The experimenters analyzed the data using the generalizability theory,with persons as the facet of differentiation and time as the facet of generalization. The major findings were (a) ventilation conditions did not have a significant impact on the reproducibility of the test scores, (b) the forearm segment produced consistently higher intracellular fluid generalizability coefficients across three ventilation conditions for both gender groups when compared to the trunk segment, (c) the trunk segment produced intracellular fluid generalizability coefficients that were higher for the male group, and (d) the measurement error affected extracellular fluid scores less than segmental intracellular fluid scores. (Contains 5 tables.)