Cryptoglandular anal fistulas (AF) cause recurrent anal abscesses and patients risk multiple surgeries due to low healing rates of sphincter-saving procedures. Knowledge of anal anatomy and imaging with MRI or endoanal sonography is crucial to classify AF as simple or complex depending on risk of anal incontinence after fistulotomy as summarised in this review. Fistulotomy has healing rates of > 90%, risks incontinence, and the procedure is reserved for simple fistulas. Complex AF are treated with a draining seton and then with sphincter-saving procedures which have long-term healing rates of about 50%.