The largest of these chains, Home Instead, opened in 1994 with six franchises and now has 722. Their 37,000 part-time workers tend to the needs of 43,000 elderly clients. The advantage is a lower hourly fee — say, $15 an hour for nonmedical needs vs. $20 an hour for a trained agency aide — and the disadvantage a scramble to find more skilled help as a patient's health declines.

Policy experts worry that the new home health care businesses could put profit above quality.

"Consumers are always in jeopardy when there's an opportunity to make a lot of money," said Val J. Halamandaris, president of the National Association of Home Care, who 40 years ago was chief counsel to the Senate Committee on Aging. "Sometimes it works out beautifully, and sometimes it doesn't. But nobody's policing it; that's for sure."

Gray-market hiring, which Meier says most of her patients choose, is largely a financial decision to avoid the fees of home-care agencies, where perhaps $9 of the $20 hourly fee goes to the aide. In a gray-market arrangement, the aide might get $12, a 33 percent increase — although sometimes without benefits, worker's compensation or Social Security — leaving a family able to afford additional hours.

Many who have hired by word-of-mouth, without criminal background checks, and paid directly cite the loyalty of employees and their ability to work unfettered by regulations. Some agencies, for example, prohibit their aides from lifting a patient who has fallen without calling 911 or getting approval from a supervisor.

That rule protects a client from being moved improperly, the aide from injury and an agency from liability. But some families shudder at the prospect of a loved one lying on the floor. Many families worry more about temperament than tasks. Meier, and most of her patients, for instance, say that entrusting someone with intimate care is less a reasoned decision than an intuition about character.

"You can teach someone how to turn a bed-bound person," Meier said, "but you can't teach the milk of human kindness."

Others say they chose gray-market employees if family members insisted upon someone of the same race. That is why Michael Elsas, president of Cooperative Home Care Associates in the Bronx, a worker-owned agency, turned to what he called "the German au pair network," rather than his own better-trained aides, for his mother. But as her Parkinson's disease progressed, Elsas said, the au pairs were not up to the task. So he hired two aides from his agency.

"The cost quadrupled," Elsas said, to $1,400 a week, from $350. Referrals from corporate employee-assistance plans and also coverage under long-term care insurance are fueling the growth of the full-service agencies.

The demand for home care aides throughout the industry is expected to outstrip supply. The Bureau of Labor Statistics counted 663,280 such aides in 2005, up from 577,530 in 1999, not counting gray-market workers. But the Census Bureau reports a stagnant number of women with little education, ages 25 to 54, the traditional labor pool for this occupation, just as the 85-and-older population is soaring.