The Patriot missile system, repeatedly proclaimed a hero of the Persian Gulf War, may not have been as effective as it once seemed, according to testimony yesterday before the House Armed Services Committee.

A total of 158 missiles, which cost an estimated $1 million each, were used to intercept the 47 rudimentary Scud missiles launched by Iraqi military forces in an unsuccessful effort to draw Israel into the war and hit vital military targets in Saudi Arabia, according to Massachusetts Institute of Technology Prof. Theodore A. Postol. Army officials confirmed the figure.

The Patriot also may have created as much damage as it prevented while intercepting Scud missiles over Israeli residential neighborhoods, said Postol, an engineer and physicist who has studied tactical ballistic missile defense issues.

In a revisionist history of events that became a nightly hallmark of U.S. technical prowess during the war, Postol testified that many if not most of the Patriot missiles fired apparently failed to destroy the Scud's explosive warheads or otherwise render the missiles harmless. While the exact number of warhead intercepts is classified, U.S. officials acknowledged that fewer than half of the Patriots evidently struck Scud warheads over Israel.

The Patriot missile intercepts, which flashed vividly on American television screens, were not protecting Israeli citizens so much as they were diverting the Scuds and their warheads from one trajectory to another, possibly equally populous target, or cutting the Scuds into large chunks still capable of inflicting casualties or destroying property when they fell to earth, Postol said.

Postol cited a summary in the Israeli newspaper Ma'ariv of the damage caused by each of the 24 Iraqi Scuds fired at Israeli cities, indicating that, contrary to public and military expectations, the number of Israeli casualties and damaged apartments rose several-fold after Patriot batteries swung into operation.

"I understand that's an upsetting conclusion, but it's possible," Postol said of his theory that the Patriot launches either may not have materially affected the net level of damage caused by the Scuds or may have increased it. He stressed that a more definitive conclusion requires additional study and access to additional government data.

Neither the Army, which manages the Patriot program, nor Raytheon Co. of Lexington, Mass., which makes the interceptor systems, contradicted the information presented by Postol yesterday. They stressed instead a mutual conviction that striking an incoming missile equipped with an explosive warhead is always better than allowing it to proceed unimpeded toward a civilian target.

"Our view is that the Patriot performed very well," said Defense Department spokesman Bob Hall. "It was quite successful in terms of hitting the missiles" in what officials say was all but two instances. Twenty-eight U.S. troops in a barracks in Dhahran, Saudi Arabia, were killed when no Patriot missiles were launched against one of the two unchallenged Scuds on the last day of the war.

"I think it was not as effective as we originally thought," House Armed Services Committee Chairman Les Aspin (D-Wis.) said of the Patriot after hearing testimony about the missile and reviewing secret information about its performance. He said it appears that the interceptors' greatest contribution "was in fact psychological," rather than military, because it symbolized a U.S. commitment to the defense of Israel that helped dampen Israeli enthusiasm for direct retaliation.

Army officials said in defense of the Patriot that it was designed to defend military targets, not urban centers, and that this task is readily met by deflection or disintegration -- not destruction -- of attacking missiles.

But several congressional aides said the Patriots' winning reputation has sharply boosted Raytheon's fortunes. Since the end of the war, Congress has approved $312 million for hundreds of new and improved Patriots sought by the Army. It also approved more than $10 million for development of a rapidly deployable variant of the missile that the Army said it does not need.

Citing the apparent effectiveness of the interceptor, former assistant defense secretary Richard Perle told the committee, "It is hard to believe that there could still be opposition to the development of a ballistic missile defense that might do for us what the Patriot did for our friends in the Middle East."