Summary A prospective randomized trial was conducted on 301 adult males undergoing inguinal herniorrhaphy to assess the value of postoperative suction drainage. Hernias were classified into ‘complicated’ and ‘simple’. In the ‘complicated’ group suction drainage for 24 h significantly reduced the incidence of wound haematoma, seroma or infection from 48·7 per cent to 17·6 per cent (P < 0·01); there was also a noticeable effect on the postoperative morbidity in the ‘simple’ hernias, although this just failed to achieve significance (4·5 per cent in the suction group compared with 9·8 per cent in the controls). It is concluded that suction drainage should be employed postoperatively following repair of hernias where dissection may be difficult or where other complicating factors are present.