The aim of the study is to compare measured glomerular filtration rate by technetium radiolabled diethylene tiamine pentaacetic acid (mGFR DTPA) to estimated GFR (eGFR). Glomerular filtration rate (GFR) is estimated from serum creatinine (eGFRcreatinine), serum cystatin C (eGFRcystatin C) and by combined equation (eGFRcreatinine + cystatin C). This study focuses on oncology patients considered for treatment with cis-diamminedichloroplatinum (cisplatin). We evaluated the impact of different GFR methods on the reduction of cisplatin dose. Patients and Methods: The study population consisted of 112 consecutive oncology patients from oncology center treated in the town of Zlin in the Czech Republic, who were considered for cisplatin treatment. mGFR DTPA was performed by dynamic renal 99mTc scintigraphy method using diethyltriaminepentaacetic acid. Creatinine and cystatin C were determined by newly standardized tests. Estimation of GFR was calculated using The Chronic Kidney Disease Epidemiology (CKD- EPI) equations which were established in 2009 and 2012. Results: The median (interquartile range) of mGFR DTPA was 1.335 ml/ s/ 1.73 m2 (1.070– 1.725). The median of eGFRcystatin C 1.195 ml/ s/ 1.73 m2 (0.885– 1.625) was lower than mGFR DTPA (p < 0.05). The median of eGFRcreatinine 1.460 ml/ s/ 1.73 m2 (1.210– 1.660) was higher than mGFR DTPA (p < 0.05). Correlation analysis and Bland- Altman plots show high individual differences between mGFR DTPA and all eGFR‘s. Conclusions: Oncology patients are a very special group of patients who diff er from general population. There are significant individual differences between mGFR DTPA and all eGFR‘s, impacting detection rate of CKD and potential drug dosage adjustment.