Ten cotton-topped tamarins (Saguinus oedipus) were infected with Moniliformis clarki a parasitic acanthocephalan. One animal died of intestinal perforation and peritonitis before treatment was initiated. Five of the remaining tamarins were treated successfully with oral albendazole at either 50 mg/kg b.i.d. for 16 days or 100 mg/kg b.i.d. for 3 days, then repeated biweekly for four treatments. A less-intensive treatment regime of 50 mg/kg albendazole orally s.i.d. for 3 days and monthly repeated treatments was unsuccessful. Parasites were removed via surgical enterotomy from two animals, both of which continued to shed acanthocephalan eggs postoperatively.