Anal fissure is arguably the most painful common anorectal disorder. The severity of pain is disproportionate to the size of the lesion (often 8–10 mm located in the posterior midline of the anal canal). Numerous surgical procedures have been advocated but Lateral Internal Sphincterotomy (LIS) has become the standard of care and the procedure of choice. Due to concerns regarding fecal incontinence (FI) following LIS various chemicals have been applied to the anal canal in hope of finding an alternative “chemical” or “pharmacological sphincterotomy”. Large numbers of studies in the literature suffer from being non-randomized case series with short follow-ups and with variable outcome measures. In 2020, LIS is the most reliable treatment for chronic anal fissure associated with almost immediate pain relief, lasting results, a very low recurrence rate, and a very small rate of postoperative FI.