Health care stocks are some of the most low-risk investments out there, since the health care industry was one of the few sectors to weather the recession with minimal disruption. After all, people still get sick no matter what the macroeconomic environment, and people will cut back on just about everything before they stop buying life-saving drugs or treatments that make them more comfortable or productive.

I watch more than 5,000 publicly traded companies with my Portfolio Grader tool, ranking companies by a number of fundamental and quantitative measures. And this week, I’ve identified seven health care stocks to buy.

Each one of these stocks gets an “A” or “B” according to my research, meaning it is a “strong buy” or “buy.”

Intuitive Surgical (NASDAQ:ISRG) designs, manufactures and markets surgical systems. In the last year, Intuitive Surgical stock has gained 56%, compared to a 4% gain for the Dow Jones in the same time. ISRG stock gets an “A” grade for sales growth, a “B” grade for earnings growth, a “B” grade for earnings momentum, a “B” grade for its ability to exceed the consensus earnings estimates on Wall Street, a “B” grade for the magnitude in which earnings projections have increased over the past months and an “A” grade for return on equity. For more information, view my complete analysis of ISRG stock.

UnitedHealth (NYSE:UNH) is a diversified health and well-being company that has experienced a stock gain of 23% in the last 12 months. UNH stock gets a “B” grade for earnings growth, a “B” grade for its ability to exceed the consensus earnings estimates on Wall Street, a “B” grade for the magnitude in which earnings projections have increased over the past months, an “A” grade for cash flow and a “B” grade for return on equity. For more information, view my complete analysis of UNH stock.

McKesson (NYSE:MCK) provides its customers with medicines, pharmaceutical supplies, information and care management products. Since the start of 2012, MCK stock has jumped 17%. McKesson stock gets a “B” grade for operating margin growth, an “A” grade for earnings growth, a “B” grade for earnings momentum, a “B” grade for the magnitude in which earnings projections have increased over the past months, a “B” grade for cash flow and an “A” grade for return on equity. For more information, view my complete analysis of MCK stock.

Aetna (NYSE:AET) is a diversified health care benefits company and is up 26% since last April. Aetna stock gets a “B” grade for operating margin growth, an “A” grade for earnings growth, a “B” grade for earnings momentum, a “B” grade for the magnitude in which earnings projections have increased over the past months, an “A” grade for cash flow and an “A” grade for return on equity. For more information, view my complete analysis of AET stock.

Humana (NYSE:HUM) has approximately 11.2 million members in its medical benefit plans and approximately 7.3 million members use its specialty products. In the last year, HUM stock has climbed 23%. HUM stock gets “B” grade for operating margin growth, an “A” grade for earnings growth, an “A” grade for cash flow and a “B” grade for return on equity in my Portfolio Grader tool. For more information, view my complete analysis of HUM stock.

HCA (NYSE:HCA) owns and operates hospitals and related health care entities. Since the first of the year, HCA stock has gained 22%. HCA stock gets an “A” grade for operating margin growth, an “A” grade for earnings growth, an “A” grade for earnings momentum, an “A” grade for its ability to exceed the consensus earnings estimates on Wall Street, a “B” grade for the magnitude in which earnings projections have increased over the past months and an “A” grade for cash flow. For more information, view my complete analysis of HCA stock.

Cerner (NASDAQ:CERN) provides its customers with health care information technology solutions, services, devices and hardware. CERN rounds out the list with a gain of 29% in the last year. Cerner stock gets a “B” grade for sales growth, a “B” grade for operating margin growth, a “B” grade for earnings growth, a “B” grade for earnings momentum, a “B” grade for the magnitude in which earnings projections have increased over the past months and a “B” grade for return on equity. For more information, view my complete analysis of CERN stock.

Get more analysis of these picks and other publicly-traded stocks with Louis Navellier’s Portfolio Grader tool, a 100% free stock-rating tool that measures both quantitative buying pressure and eight fundamental factors.