Planning Research Corp. said yesterday its profits rose 29 percent in the year ended June 30 despite a 2 percent decline in revenues.

The McLean-based professional services company said the effects of the recession and project deferrals by customers were behind the drop in sales, while improvements in operating efficiencies and interest expense pushed earnings higher.

PRC reported net income of $9.1 million ($1.30 per share) in the fiscal year, up from $7.1 million ($1.04) in fiscal 1982. Revenues were $318.1 million, compared with $324.1 million a year ago.

In its fourth quarter, PRC said it earned $2.5 million (35 cents), up 41 percent from $1.8 million (26 cents) a year ago. Revenues dropped 4 percent in the period to $81.8 million from $84.8 million.

Hazleton Laboratories Corp., a Vienna-based biological products and services firm, said its revenues rose 25 percent in the year ended June 30 to $70.4 million, from $56 million a year ago, but earnings were unchanged at $2.6 million due to a decline in interest income. Earnings per share declined to 70 cents, from 73 cents, because of an increase in the number of the company's shares outstanding.

Radiation Systems Inc., a Washington-based maker of antennas used primarily in air-traffic control, said its profits increased 46 percent to $3.5 million (80 cents) in the year ended June 30 from $2.4 million (56 cents) a year earlier. Sales rose 45 percent to $22.2 million from $15.3 million.