After renal transplantation (RTx), an increase in body weight (BW) is usually observed, in which corticosteroids may play an important role. However, the effects of a low maintenance dosage of corticosteroids on BW have not been studied longitudinally in RTx patients. The aim of this study was to compare changes in BW after RTx in patients on steroid- or steroid-free immunosuppressive therapy and to assess the relationship between post-transplant weight changes and other potentially important factors. The charts of 123 RTx patients (72 male, 51 female) were retrospectively examined for BW changes in the first 5 years after RTx. Sixty-six patients were on 5-mg maintenance steroid dose and 57 patients underwent steroid-free immunosuppression. Mean post-transplant BW gain was 3.0+/-5.3 kg after 6 months, 3.9+/-6.2 kg after 1 year and 6.2+/-8.6 kg after 5 years. Weight gain in the first year after RTx was related neither to maintenance- nor to cumulative steroid dose, age, gender, occurrence of rejection, or renal function. Weight gain was, however, significantly related to pre-transplant BMI and dialysis modality. After the first year, weight gain was significantly and positively related only to the cumulative steroid dose. The course of weight gain in the first year after RTx turned out to be independent from factors such as maintenance- or cumulative steroid dose, age, gender, occurrence of rejection, and renal function; weight gain was, however, dependent on pre-transplant BMI and dialysis modality. After the first year, the weight course was significantly affected by cumulative steroid dose.