Abstract This case report reaffirms the findings in other cases reviewed, that complications may arise when mercury is free in the intestinal tract and a break in continuity exists. In the case reported herein, mercury freed from a balloon escaped through the anastomotic line and interfered with healing of the anastomosis. A perirectal abscess and a rectovaginal fistula developed which, before the process was eradicated, resulted in a chronic mercury granuloma and a rectoperineal fistula. Complete and extensive excision of the granuloma in stages was done before final cure was accomplished.