Following are excerpts from the resignation statement of Justice Lewis F. Powell Jr.:

I have advised the chief justice and associate justices that I have elected to retire as an associate justice. The president will be advised today.

This is a decision I have made quite recently, but after careful thought. Although I was reluctant to come to the court at age 64, this institution -- apart from my family -- has been my life now for 15 1/2 years. My respect for it as a unique institution has been enhanced by the privilege of serving here. I will miss being an active justice more than I can say. I summarize briefly, in no particular order, my reasons for retiring at this time:

1. On Sept. 19, I will be 80 years of age. I believe I said some years ago that it would have been wise for the Founding Fathers to have required retirement of federal judges at a specified age, perhaps at 75. Of course, such a limitation would have deprived the court of the service after that age by a number of the most distinguished justices ever to sit on this court. I specifically include present brothers among this group. But for me, age 80 suggests retirement.

2. When President Nixon requested that I accept appointment to the court, in addition to expressing my reservation about appointing anyone to this court at age 64, I stated that if I were confirmed I would not expect to remain on the court for more than 10 years. As former chief justice {Warren} Burger will confirm, I seriously considered -- and discussed with him -- retirement at the end of June 1982. Our children, two of whom are lawyers, persuaded me not to retire. In retrospect, I am glad I remained an additional five years.

3. My health has not been "robust." I have undergone major surgery three times since coming to the court, including prostate cancer surgery at Mayo in 1985. I have had regular semiannual checkups at Mayo and underwent the full range of tests there earlier this month. Happily, all tests were favorable, and both of the physicians in charge concluded that I am presently in good health. But my past illnesses have created problems for the court and for litigants.

In sum, I am motivated by (i) the imminence of my 80th birthday, (ii) by having served 15 1/2 years when I contemplated no more than 10 years of service, and (iii) by concern -- based on past experience -- that I could handicap the court in the event of reoccurrences of serious health problems.