The THO complex 1 (Thoc1) is a nuclear matrix protein playing vital roles in transcription elongation and mRNA export. Recently, aberrant expression of Thoc1 has been reported in an increasing array of tumor types. However, the clinical significance of Thoc1 expression in colorectal cancer (CRC) is still unknown. The present study aimed to characterize the expression of Thoc1 in human CRC and evaluate its clinical significance. Quantitative real-time polymerase chain reaction (qRT-PCR) and Western blotting analyses showed that the mRNA and protein expression of Thoc1 in CRC specimens was significantly higher than that in adjacent normal colon mucosae. Immunohistochemistry (IHC) was conducted to characterize the expression pattern of Thoc1 in 185 archived paraffin-embedded CRC specimens. Statistical analyses revealed that high levels of Thoc1 expression were associated with the clinical stages and tumor differentiation. CRC patients with high levels of Thoc1 expression had poorer overall-survival and disease-free survival, whereas those with lower levels of Thoc1 expression survived longer. Furthermore, multivariate Cox regression analyses demonstrated that Thoc1 expression remained an independent prognostic factor for increased disease recurrence and decreased survival. Our results suggest for the first time that Thoc1 is involved in the development and progression of CRC, and elevated expression of Thoc1 is associated with aggressive phenotype and poor prognosis in CRC. These findings may prove to be clinically useful for developing a new therapeutic target of CRC treatment. (C) 2015 Elsevier Inc. All rights reserved.