Aim: To evaluate the quantitative detection of human telomerase RNA (hTR) and human telomerase reverse transcriptase (hTERT) mRNA as diagnostic parameters in the workup of testicular tissue specimens from patients presenting with non-obstructive azoospemia. Methods: hTR and hTERT mRNA expression were quantified in 38 cryopreserved testicular tissue specimens by fluorescence real-time reverse transcription- polymerase chain reaction (RT-PCR)in a LightCycler(r). This was paralleled by conventional histological workup in all tissue specimens and additional semithin sectioning preparation in cases with maturation arrest ( n = 12) and Sertoli-cell-only syndrome ( n = 12). Results: The average normalized hTERT expression (NhTERT) Was 131.9 ± 48.0 copies (mean ± SD) in tissue specimens with full spermatogenesis, NhTERT = 51.2 ± 17.2 copies in those with maturation arrest and NhTERT = 2.7 ± 2.4 copies in those with Sertoli-cell-only syndrome (SCOS). The discriminant analysis showed that detection of NhTERT (NhTR) had a predictive value of 86.8 % (55.3 % ) for correct classification in one of the three histological subgroups.Conclusion: Our results demonstrate that quantitative detection of hTERT mRNA expression in testicular tissue enables a molecular-diagnostic classification of gametogenesis. Quantitative detection of hTERT in testicular biopsies is thus well suited for supplementing the histopathological evaluation.