Dr. Murdock Head pleaded innocent yesterday in U.S. District Court in Alexandria to charges of conspiracy, tax evasion and bribery in connection with the tax-exempt Airlie Foundation he directs in Warrenton, Va.

Head, 55, dressed in a hand-tailored blue suit and wearing a gold bracelet on his right wrist, stood at attention in the nearly empty courtroom as Judge Albert V. Bryan Jr set trial for Sept. 10 and freed Head on $5,000 bond.

Head's only comment during the eight-minute hearing was to answer "I do" when asked if he intended to return for the trial.

Head, who is also a George Washington University physician and department head, has often hosted government officials and VIPs at federally funded conferences at Airlie, about 45 miles southwest of Washington.

Yesterday's arraignment was Head's first public appearance since a federal grand jury in Alexandria returned a 22-page, 13-count indictment against him on Thursday.

In the indictment, Head is accused of paying bribes to Rep. Daniel Flood (D-Pa.), former congressman Otto Passman (D-La.) and Flood's former aide, Stephen B. Elko, in exchange for help in obtaining federal grants for Airlie Foundation projects.

Head also allegedly aided in the preparation of false income tax returns on behalf of the foundation for 1974, 1975 and 1976, and gave a gratuity to an Internal Revenue Service agent involved in an Airlie audit, according to the indictment.

Bryan yesterday set July 27 and Aug. 24 for hearing pretrial motions in the case. If convicted, Head could face 15 years in prison and $20,000 in fines on the bribery charges and lesser penalties on the other counts.

After the hearing, Head, accompanied by his attorneys, Brian P. Gettings and Frank W. Dunham, posed for a photographer before getting into a station wagon with the Airlie crest on its door and the license plate "AIR-2."

Removing his jacket and revealing bright red suspenders as he entered the car, Head joked, "I may have to sell these" to raise money.