Objective: Patients receiving regular hemodialysis have a lower body mass index, which is mainly caused by the reduction of fat mass and body cell mass (BCM) and the accompanying extracellular water (ECW) expansion. Kidney transplant (Tx) recipients normally regain subnormal renal filtration, and they must cope with significant therapeutic-associated metabolic side effects, which may compromise the recovery of normal nutritional status. We investigated the influence of renal function recovery on body fluid composition during the first period post-Tx, when immunosuppressive drugs doses are at their highest. We also analyzed the differences between males and females and compared them with healthy controls. Methods: Eighteen patients (11 males and 7 females) were studied. Biolectric impedance analysis was done pre-Tx and at months 1 and 3 post-Tx. We considered the following parameters: total body water, ECW, intracellular water, Na:K exchangeable ratio, phase angle, and BCM. The healthy group was evaluated three times in a year interval. Results: We observed differences between genders. Compared with healthy males, resistance, reactance, intracellular water, and BCM were greater and ECW was lower among Tx males at pre-Tx time. At months 1 and 3, we observed only different total body water in males compared with controls. Females did not display any differences in biolectric impedance analysis parameters compared with healthy controls, with the exception of lower reactance at month 1. Conclusions: Compared with healthy subjects, uremic males presented body water disturbances pre-Tx. During the first 3 months post-Tx, males showed an incomplete recovery of bioelectric impedance analysis parameters with a greater total body water, probably the result of drug therapy side effects. Pre-Tx, Tx females at pre-Tx time had no differences as compared with healthy females. (C) 2007 by the National Kidney Foundation, Inc.