All surgical procedures carry some risk. 

Complications following a hernia repair in the groin include:

Bleeding/haematoma

Wound infection

Recurrence - <2% in the short term but this can increase to 5% over a long period of follow-up

Chronic groin pain - this has been found to be more common in patients who have significant pre-operative pain, younger patients and those who have operations for recurrent hernias

Urinary retention

Injury to the contents of the spermatic cord

Entrapment neuropathy

Testicular atrophy