Objectives To present the most serious complications from circumcision and to compare the complications caused during mass and single circumcisions performed by medically trained or untrained operators. Patients and methods The study comprised both a retrospective and prospective analysis of 220 cases of complications from circumcisions occurring during the last decade and a comparison of the frequency and distribution of complications in mass (n=700) and single (n=600) circumcisions. Results Traditional (medically untrained) circumcisers were responsible for 85% of the complications and almost all the disastrous ones. The frequency of complications from mass circumcision was statistically significantly higher than that from circumcisions performed singly in operating room conditions (relative ratio 3.05 and P<0.001). Conclusion Circumcision can have serious life-threatening and prolonged complications. It should only be performed in medical institutions by suitably trained surgeons. Mass circumcisions organized for any purpose carry significantly greater risk and should be prevented.