A surgical instrument for use in hernia repair comprises an elongate tube having a distal end and a proximal end and a balloon attached in a collapsed configuration to the tube at the distal end, the balloon being made of a material which is absorbable by the human body. A net which envelops the balloon is also attached to the tube at the distal end thereof. During a hernia repair operation, the tube is used to insert the balloon from the abdominal cavity of a patient through a hernial opening in an abdominal wall of the patient and into a hernial pocket in inguinal tissue. After the balloon has been so inserted, it is inflated, which expands the net, and the abdominal wall opening is subsequently sealed. A mesh of biologically inert polymeric material for inducing human tissue growth is attached to the abdominal wall over the opening therein. The peritoneal tissue is stapled closed over the sealed opening in the abdominal wall.