OBJECTIVE: To determine the early rapid diagnosis of renal tuberculosis (RTB) by real-time polymerase chain reaction (PCR) on renal biopsy specimens. METHODS: Ninety patients were selected for this study. The patients were divided into the following three groups: RTB, non-RTB (N-RTB) and clinically suspected RTB (CS-RTB). The renal biopsy specimens of these patients were used for Mycobacterium tuberculosis DNA detection by real-time PCR, using 35 and 40 as cycle threshold (C_T) cut-off values. Morning urine samples were collected for M. tuberculosis culture. RESULTS: In the RTB group, 25 C _T35 and 28 C_T40 patients were PCR-positive, seven of whom were urine M. tuberculosis culture-positive. In the N-RTB group, four C _T35 and 13 C_T40 patients were PCR-positive, none of whom were urine M. tuberculosis culture-positive. In the CS-RTB group, nine C _T35 and 14 C_T40 patients were PCR-positive, two of whom were urine M. tuberculosis culture-positive during 12 months of follow-up. The sensitivity and specificity of real-time PCR (C_T40) were respectively 93.3% and 56.7%. The sensitivity and specificity of real-time PCR (C _T35) were respectively 83.3% and 86.7%. The sensitivity and specificity of the urine M. tuberculosis culture were respectively 23.3% and 100%. CONCLUSIONS: The detection of M. tuberculosis DNA in renal biopsy tissue by real-time PCR is highly sensitive. Real-time PCR can increase diagnostic accuracy and provide valuable information regarding the early diagnosis of RTB. © 2010 The Union.