The end of rent controls in Montgomery County has brought Elsie Bliss a 66 percent rent increase and similar rises for some of her neighbors -- amounts that officials say may prompt the County Council to freeze rents countywide.

The 51-year-old Silver Spring resident has received notice of one of the highest increases in Montgomery for her two-bedroom unit in the Rollingwood Apartments. Her rent is going from $235 to $390 a month. Neither amount includes utilities.

Like Bliss, most Rollingwood tenants live on moderate incomes. The 40 tenants who have the dubious distinction of getting Montgomery's highest rent increases since decontrol will be hard pressed to pay the higher rates, or to find other housing at the old Rollingwood rent levels.

Rent-control laws in Montgomery County expired at the end of January, amid County Executive Charles W. Gilchrist's assurances that landlords would not raise rents higher than 10 to 15 percent and tenant-association warnings that the demise of regulations would send rents to unprecedented heights.

With a 60-day notice requirement, rent increases effective April 1 are the first ones since the end of rent-control laws. In all, rent hikes on 4,000 units were reported for April 1 and 75 percent were within the guidelines. Some landlords among the 25 percent who went over the guidelines have since rolled back their original increases. Others were given permission last year to increase rents for 1981 to pay for major renovations.

Then the May 1 notices came out, and Rollingwood tenants were informed of their increases.

"It's absolutely unconscionable," said Richard Ferrara, director of the county's Office of Landlord-Tenant Affairs. "The County Council could get upset and vote for a rent freeze, and then everybody suffers because one outfit is greedy.

These are "the first extremely large rent increases (that) could not be explained, other than they (the management) want to bring all rents up to the same level. If this were to go into effect without the start of a whole series of astronomical rent increases," he said.

Ferrara said he is keeping the County Council and the county executive informed of the rent increases.

When Gilchrist in January vetoed bills that would have extended the county's 8-year-old rent-control laws, he said the restrictions contributed to the trend toward condominium conversaions.

He said the owners of 70 percent of the county's 39,000 rental units had voluntarily pledged to stay within a 10 percent annual increase for apartments not previously under the controls, and within a 15 percent increase for the 16,000 apartments coming off rent control.

Ferrara said tenants have no legal recourse. "The best tactic we have is to make landlords aware of the potential reaction from the County Council so that they'll say to the ones who are going over the guidelines, 'look, you're endangering all of us.' We'll do everything possible to pressure them to roll the rents back."

At Rollingwood, a 282-garden-apartment complex on Ross Road, rents are being increased so that, exclusive of utilities, rents for all three-bedroom apartments will be $425 to $445 a month. Two-bedroom apartments will be $355 and efficiencies $310.

One single-bedroom apartment that was under rent control is going up from $227 to $310 a month, not including utilities.

Steve Guttman, president of Federal Realty Investment Trust, which owns Rollingwood, said he had no comment on the rent hikes.

The president of the management company for the complex, Leslie Fleisher of Investor Service Management Inc., would say only that the rent increases were made according to normal procedures.

"It's about as high as I've heard of," said council member Neal Potter. "And if it's plus utilities, it's even worse. Those are nice, modest apartments. It would be too bad if they increase rents by that much. It would knock a lot of those people out."

He said he had indicated earlier that he would consider introducing an emergency bill if the rent guidelines were not observed.

Bliss, who has lived in Rollingwood 12 years, said she does not want to move, despite her fear of going to the unlocked laundry room at night, her inability to get repairs or improvements made in her apartment, and the rising cost of heating and cooling an apartment that is drafty in winter and steamy in summer.

"But this is my haven," she said. "The only good thing about my life was that this was controlled. After 20 years of working in Washington and raising a child on my own, I hadn't been able to get permanent housing. Now my survival is threatened, and I don't think this is an overstatement."