We report on a clinicopathologic study in an animal model of treatment with a new bioabsorbable polymer plug (BAPP). Over a 2-week period, 6 porcine models, which each had 4 anal fistulae, were created using Blake drains. The pigs were divided into 2 groups: the BAPP-treatment group (n = 12 fistulae) and the control group (n = 12 fistulae). Two weeks later, the pigs were humanely killed, and the perianal sites were excised and examined with gross and pathologic studies. Each fistula in the BAPP group was completely cured. In the pathologic study, the treatment sites had little disarray, few defects in the muscular layer, and small numbers of inflammatory cells. The control group had a significantly greater number of inflammatory cells and microabscesses than the BAPP group. The newly developed BAPP reduced the infection and induced good healing in anal fistulae. The BAPP may be a useful new device for the clinical treatment of anal fistulae.