After selling some of its stake last year, Berkshire Hathaway (NYSE: BRK-A) (NYSE: BRK-B) has once again become a buyer of health-care giant Johnson & Johnson (NYSE: JNJ). During the second quarter, Warren Buffett bought 17.4 million shares of the health-care giant. At yesterday's close, that's a cool $1 billion on top of the $1.4 billion he already owned.

It's pretty clear what the Oracle of Omaha sees in Johnson & Johnson: the diversified health-care giant is as cheap as it's ever been. Pick your favorite valuation metric:

Metric

2004

2005

2006

2007

2008

2009

Current

Enterprise Value/Revenue

3.65

3.74

3.36

3.30

2.92

2.56

2.50

Price/Book Value

5.80

7.71

4.64

4.46

4.06

3.51

3.09

Price/EPS

20.71

21.62

17.21

17.73

16.27

12.68

12.26

Source: Capital IQ, a division of Standard & Poor's. Average valuation for years indicated.

So should you follow Buffett's lead? Only if you have the same time horizon -- how's forever sound to you? -- and I'm not sure you need to buy as quickly as Buffett did. Keeping in mind, we don't know if he's done yet.

Like its pharma compatriots -- Pfizer (NYSE: PFE), Bristol-Myers Squibb (NYSE: BMY), and Eli Lilly (NYSE: LLY) in particular -- much of the lower valuation is due to current and future patent expirations that have slowed growth. But Johnson & Johnson has also been knocked down by myriad recalls recently.

I think there's an excellent chance that Johnson & Johnson turns things around. You don't get too many chances to buy excellent companies at beaten down prices, but I'm not convinced it's going to be a quick turnaround either.

The loss of revenue from its recall-related plant closure isn't the major problem -- that only amounts to about 1% -- but the quality control issues are going to take a lot of management's focus that could be spent working on ways to increase revenue and expand margins.

The best way to play Johnson & Johnson may be to buy in over time, enjoy the solid 3.6% dividend yield, and realize you're in good company.

Johnson & Johnson is a Motley Fool Income Investor selection and Motley Fool Options recommended a diagonal call position on the stock. Berkshire Hathaway and Pfizer are both Inside Value recommendations while Berkshire is also a Stock Advisor selection. Plus, the Fool owns shares of Berkshire Hathaway. Pfizer is a recommendation of the Inside Value newsletter.

Fool contributor Brian Orelli, Ph.D., doesn't own shares of any company mentioned in this article. The Fool has a disclosure policy.