Washington Bullet guard Kevin Porter, who led the National Basketball Association in assists last season, suffered a torn Achilles' tendon in his left leg in practice yesterday and will miss the entire season.

Porter, 31, underwent surgery last night at George Washington University Hospital. Team physician Steve Haas, who repaired the tendon in a 1 1/2-hour operation, said Porter will be hospitalized three days and will have to wear a cast for six to eight weeks.

The Bullets also said that forward-guard Carlos Terry would be out at least 10 days with a wrenched left knee. He injured it in Saturday's intrasquad scrimmage at Dunbar High School.

The loss of Porter, a nine-year NBA veteran, means that Frank Johnson, the team's No. 1 draft choice out of Wake Forest, will not have the luxury of learning Porter's position as a reserve. The Bullets considered Porter the key to their fast-breaking offense.

"That's the whole reason we drafted Frank," General Manager Bob Ferry said. "We feared what would happen if something happened to Kevin. We certainly hoped nothing like this would happen."

Ferry said that "right now" a trade to improve the position was unlikely.

Contacted last night and asked whether it was likely Johnson would start when the season opens Oct. 30 at Boston, Coach Gene Shue said: "It's not likely at all. At this point I have no idea."

Other guards in camp who can play the point are veteran Andre McCarter, Porter's backup last season; Brad Holland, obtained from the Lakers in the Mitch Kupchak deal, and Ed Odom, a free agent from Oklahoma State.

"KP has been a terrific player. He had an exceptional year last season playing his style of basketball," said Shue. "We don't have a lot of veteran players, and I was counting on him to blend in with the younger players. It's a big loss to our team."

The injury to Porter occurred in a defensive drill near the end of the morning practice at Bowie State College, according to John Lally, team trainer. As Porter pivoted after Ricky Mahorn handed him the basketball, he felt something pop and fell to the floor.

"I was standing right next to him," said Shue. "He tried to get up and said, 'What happened?' "

"(Then) he said, 'I think it's gone,' " said Johnson, who was standing nearby. "I thought he was talking about his ankle."

Haas, who had attended practice in order to check Terry and other players with minor injuries, immediately diagnosed Porter's injury.

"He's definitely out for the season," said Lally. "A number of players, including Phil Smith (then with the Golden State Warriors) two years ago, have come back from it (a torn Achilles' tendon)."

Shue said he had not seen enough of Johnson to determine whether he can replace Porter by the start of the season.

"He's only been with the team two days," Shue said. "We really benefited by having the (young) players in during the summer. But Frank missed that and a good part of training camp. It's really catch-up."

Johnson reported to training camp only last Friday, after settling on the terms of a five-year contract and receiving clearance to play after a physical examination revealed he has hypertension. He played briefly in Saturday's scrimmage and looked rusty.

"I was so unsure about the plays. . . I was just standing around," he said yesterday. "A lot of it is instinct and timing, which you can't get standing on the sidelines.

"Today was like the second practice, but I feel I've made a lot of progress . . . I'm very disappointed that Kevin had to get hurt. It's an opportunity for me to play that I wasn't looking for right away, not like this anyway. But it's there . . ."

Johnson said his major problems will be timing and getting used to the other players.

"Everybody has been pretty patient," he said. "They can't have too much more patience now . . . I have to pick up things quicker now. Now I have to do it."