Abstract: Objective　To study the position and morphological features of the arcuate line and get better understanding of its clinical significance, so as to provide the applied anatomical data and operation guide for the totally extraperitoneal (TEP) herniorrhaphy.    Methods   The arcuate line was dissected and observed during TEP in 60 cases of adult patients with primary inguinal hernia. The location and length of the arcuate line were determined by puncturing needle vertically through the skin, and its morphology and quantity data were recorded.　Results　The arcuate line was recorded and divided into four groups, namely, a classical group (4~5 cm) in 15 cases (accounting for 25.0%), a high level group (less than 3 cm) in one case (accounting for 1.7 %), a low level group (6~12 cm) in 43 cases（accounting for 71.6%）, an absent arcuate line group in one case (accounting for 1.7%). Twenty-two cases were single arcuate line (accounting for 36.7%), while 38 cases were multiple arcuate line (accounting for 63.3%). Two cases were the straight shaped arcuate line (accounting for 3.3%), 28 cases and 29 cases were the arc-shaped and the transition shaped arcuate line  (accounting for 46.7% and 48.3 %  respectively).    Conclusions     The arcuate line is the free margin formed by the absence of the posterior layer of the rectus sheath. There are great differences in its position, morphology and number. The variation of arcuate line not only increases the difficulty of the TEP surgery, but also increases the complications. The arcuate line has important clinical significance in the TEP operation.

Key words: Arcuate line, 　TEP, 　Inguinal hernia, 　Anatomy, 　Morphology