BACKGROUND Both adiposity and underweight are negatively associated with graft and patient survival after kidney transplantation (KTx). The aim of this longitudinal study was to evaluate the changes in body mass index (BMI) after KTx and their relations with graft damage markers. MATERIAL AND METHODS The anthropometric measurements of body mass and height were performed in 92 consecutive deceased donor kidney transplant recipients (37 F; 55 M) from a single transplant center. Patient medical history, estimated glomerular filtration rate (eGFR), serum lipids, and ACR (urine albumin-to-creatinine ratio) was obtained from medical charts. RESULTS KTx recipients were on average 3.4±2.5 years after transplantation. Mean body BMI before KTx were 25.3±4.3 kg/m2 and increased after transplantation to 27.0±4.6 kg/m² (p=0.01). BMI increase after KTx was noted in 65% of recipients, most often in patients with normal pre-KTx BMI. Kidney function was better in patients with normal post-KTx BMI (55.2±15.8 ml/min/1.73 m²) than in obese patients (48.0±20.3 ml/min/1.73 m², p<0.05). Patients with normal post-KTx BMI had lower ACR (31.9±18.1 mg/g) than overweight (117.4±53.6 mg/g, p<0.05) and obese patients (280.0±81.7 mg/g, p<0.05). There were no differences in the mean BMI changes in recipients who received cyclosporine A or tacrolimus. CONCLUSIONS Patients after KTx showed an increase of BMI greater in those with normal pre-transplant body mass. The change in BMI over time has no effect on the graft function or magnitude of albuminuria. Overweight and obese patients after KTx have higher albuminuria and worse graft function than those with normal BMI. The type of calcineurin inhibitor has no effect on body mass after KTx.