Perianal abscesses (PA) are relatively common in children, especially in infants. The aetiology of PA is still unknown but several factors point toward a congenital aetiology: 1) it is almost exclusively seen in infants, 2) with a male predominance, 3) predilection sites at 3 and 9 o'clock, 4) the finding of abnormal Morgagni crypts and 5) aberrant epithelial lining. Traditionally, incision and drainage has been the treatment of choice, but several studies suggest conservative management. The effect of antibiotics has not been proven. In this case report we present two 29-day-old monozygous twin boys with PA.