Circumcision for men
Question

Is circumcision mandatory for the man who adopts Islam?  What is the Islamic rule on female circumcision?
Praise be to Allah.  To the dear inquirer:
We appreciate the question you have submitted, as it is an issue which is truly among those which may pose a hindrance in some cases for those who wish to adopt Islam.
In reality the issue is really simpler than many may think.  Male circumcision is among the rites of Islam and is part of the fitrah, or the innate disposition and natural character and instinct of the human creation, and is from the religion of Ibrahim (peace be upon him).  Allah has said (interpretation of the meaning): "Then we revealed to you (the command) to follow the pure and uncorrupted religion of Ibrahim." 
The Prophet  (peace be upon him) said: 
"The Prophet Ibrahim (peace be upon him) was circumcisized when he was eighty years old." (Al-Bukhari, Vol 6/p. 388, Al-Salfiyya printing).
Male circumcision is obligatory for the Muslim male if he is able to do it.  If, however, he is unable, whether due to fear of injury or if a respected and authoritative doctor has told him he will experience profuse bleeding which may make his life miserable, then the obligation for cirumcision is waived and he does not commit a sin by not having it done.
It is not permissible under any circumstance for the issue to become a hindrance for a person wanting to accept Islam.  The validity of one's acceptance of Islam is not dependent on his performance of circumcision and it is valid for one to adopt Islam even if he has not had himself circumcized.
Regarding the issue of female circumcision, please refer to question # 427 .
I ask Allah to bring you success in all that is good and to protect you from all that is evil, and may the peace and blessings of Allah be upon our Prophet Muhammad  .