In an article in yesterday's editions about Supreme Court Justice William J. Brennan Jr., the Associated Press erroneously reported that retired justice Lewis F. Powell Jr. suffered prostate trouble this year. Powell had a cancerous prostate removed in 1985 and returns annually to the Mayo Clinic for a checkup, according to a court aide. (Published 8/12/87)

Justice William J. Brennan Jr., the Supreme Court's senior member and leading liberal, is following the advice of two justices with prostate cancer by being tested at the Mayo Clinic for prostate trouble, a court spokeswoman said yesterday.

Spokeswoman Toni House said it is not believed that Brennan's prostate problem, which developed last spring, is due to cancer.

"If things go as anticipated, I expect to undergo a routine prostate procedure later this week," Brennan, 81, said in a statement. "I plan and fully expect to participate in the court's October term."

Brennan, who arrived Sunday at the clinic in Rochester, Minn., is expected to remain there at least through this week and most likely will undergo a transurethral resection, a clinic spokesman said. President Reagan underwent a similar procedure in January.

Justices Harry A. Blackmun and Lewis F. Powell Jr. each were diagnosed this year as having prostate cancer and were treated at the clinic. Powell, 80, resigned in June, citing the potential of a recurrence of his health problems. Blackmun, 78, finished the first half of his treatment last week and plans to return next month to complete it.

House said Brennan's prostate trouble started last spring and that he decided to seek testing at the Mayo Clinic because Blackmun and Powell had recommended it.

Brennan's statement said additional information on his condition will be released after tests are completed.

The prostate is a muscular gland at the base of the bladder. Cancer of the prostate is one of the most common forms of cancer and occurs frequently in men older than 60.

In 1979, Brennan had a stroke that left his right hand partially paralyzed and, a year earlier, he was treated for a cancerous growth on a vocal cord.

Brennan was appointed to the court by President Dwight D. Eisenhower in 1956.