Phimosis of the foreskin after radiotherapy for rectal carcinoma is extremely rare and has previously been described only once (2006) in the English-language literature. Combination chemo/radiotherapy is currently the treatment of choice and widely used in the management of various pelvic malignancies. In this report, we describe a rare complication on male genitalia following the radiotherapy for lower rectal cancers. Few days following the completion of radiotherapy, patient developed phimosis of the foreskin, which was successfully treated medically without the need for circumcision. Radiotherapy can bring a great risk of injury to anorectum and its adjacent structures. Risk of phimosis should be considered under the current radiation guidelines and we support the concept of using penile shielding for all radiotherapy procedures in colorectal carcinoma patients.