AbstractGroin dissection was performed in adult male post‐mortem subjects to establish the prevalence of inguinal canal ‘lipoma.’ Thirty‐six body halves (age range 24–92 years) were studied. Of these, 27 (75%) contained a discrete mass of fat within the inguinal canal. This mass was always continuous with the preperitoneal fat through the deep inguinal ring. Nineteen of these 27 masses (70%), displayed a characteristic pedunculated form with a bulbous distal end. Eighteen of the 36 dissections (50%), revealed a mass more than 4 cm in length. Six dissections showed extension of the mass beyond the superficial inguinal ring and three of these six (8% of the 36 groins studied) showed distortion of the proximal spermatic cord with a mass at the superficial inguinal ring. The masses submitted for histology comprised mature adipose tissue and all but two of these were reported as having an adherent capsule. No significant correlation was found between mass length and either subject age or body mass index (BMI) but a statistically significant correlation between the length of the fat mass on the left and right sides was shown. This study demonstrates that the inguinal canal ‘lipoma’ is a common feature in an adult male population and may be of sufficient size to cause clinical misdiagnosis. The high prevalence, characteristic location and appearance of the ‘lipoma’ suggest a developmental etiology. Clin. Anat. 15:280–285, 2002. © 2002 Wiley‐Liss, Inc.