The stabilization of telomere length by telomerase activation is an important step in carcinogenesis. Quantification of the catalytic telomerase subunit hTERT (human Telomerase Reverse Transcriptase) is a new indirect measure for telomerase. Telomere length and hTERT expression in cancer tissue and corresponding normal mucosa of 57 patients with completely resected colorectal carcinoma (UICC stage I-IV, R0) were determined for correlation with histopathological parameters and survival. Telomere lengths were measured using Southern Blot and hTERT-encoding mRNA was quantified by real-time RT-PCR. Telomere length and hTERT expression were significantly correlated in normal mucosa and cancer tissue (p<0.001). Telomere length and hTERT expression decreased with ageing only in normal mucosa. Cancer tissue had significantly shorter telomeres (p<0.001) and significantly lower hTERT expression levels (p<0.001) than corresponding normal mucosa. UICC stage I tumors showed significantly shorter telomeres than UICC stage II-IV tumors (p<0.002). Telomere length and hTERT expression were significantly correlated with overall survival. Telomere length and hTERT expression play an important role in ageing and carcinogenesis. Both parameters were identified as prognostic factors in patients with colorectal carcinoma.