radiotherapy is an important discovery as to the treatment of pelvic tumors. proctitis is frequently observed nowadays, and can be divided into acute and chronic. treatment with 4% formalin solutions has been used with positive results in literature. objective: to evaluate the effectiveness and morbidity rates related to the use of 4%formalin in hemorrhagic chronic actinic proctitis. methods: we evaluated the sigmoidoscopy records and reports of 11 patients with chronic hemorrhagic actinic proctitis from february to december 2010, coming from the serbian colorectal university hospital of the state of sergipe. results: the study was comprised of 11 patients (36.36% were females and 63.63% were males). mean age was 67.7 years. mean time between the end of radiotherapy and the onset of symptoms was 6.6 months. the treatment was completely effective in 27.27% of the cases, and reduced rectal bleeding in 100% of patients. the following main complications were observed: chills (9%), tenesmus (18.18%) and mild stenosis (9%). conclusions: the 4%formalin solution has fewer side effects, and its administration is very inexpensive. the treatment is effective and reduces bleeding in almost 100% of cases.