Aims: To determine sperm nuclear DNA integrity and to investigate the relation between fenvalerate(FE)exposure and spermatozoa DNA damage. Methods: Sperm DNA fragmentation was detected by a modified alkaline single cell gel electrophoresis (Comet) assay and a terminal deoxynucleotidyl transferase mediated dUTP nick end labelling (TUNEL) assay. The olive tail moment (OTM) and percentage tail DNA were measured by the Comet assay, and cell positive percentage was measured by the TUNEL assay for DNA damage evaluation. Results: he DNA integrity of spermatozoa of external and internal control groups were both significantly greater than that of the FE exposed group. The median value of tail DNA percentage in the exposure group was 11.30, which was significantly higher than 5.60 in the internal control group and 5.10 in the external control group. The median value of OTM was 3.80 in the exposure group, significantly higher than 1.50 in the internal control group and 2.00 in the external control group.Mean cell positive was 31.2% in the exposure group, significantly higher than 17.4% in the internal control and 19.6% in the external control groups.Cell positive (%) was significantly correlated with tail DNA percentage and with OTM of whole subjects (n=63). Conclusions:Results showed that occupational FE exposure is associated with an increase in sperm DNA damage.A combination of the Comet and TUNEL assays would offer more comprehensive information for a better understanding of sperm DNA damage,and the biological significance of sperm DNA damage in sperm function and male infertility.