Health care funds are far and away this year's top-performing pack, but buying a chart topper might be biting off more risk than you can chew.

Because sector funds focus their investments on one industry or even a thin slice of it, they're often feast-or-famine performers. This year health care funds have been feasting. So far they're outperforming every other fund category, up more than 50%, compared to a 7.2% dip for the

S&P 500, according to

Morningstar

.

But all health care funds are hardly alike. As sector-fund investing has become more popular, fund companies have diced the sector into thin slices to stand out from the crowd. Now in addition to funds that spread their money across the sector, there are funds that focus on the biotech, genomics and medical-delivery industries. Because these funds are even more dependent on a thinner band of health care stocks, they're even more risky than the average health care fund and usually land at the top or bottom of the category.

Today, biotech-heavy funds are top dogs because cutting-edge drug makers' shares have sizzled of late. Over the past year the

American Stock Exchange Biotechnology Index

is up more than 140%, according to

Baseline

. Consequently, if you use today's scoreboard to shop for a health care fund, you're probably buying what is essentially a biotech fund, along with a slew of risk. Only five health care funds have topped their average peer over the past one- and three-year periods, and each is either a biotech fund or carries a healthy dose of biotech stocks in its portfolio.

If you're looking for access to biotech, poke through these funds. If you're a

no-load investor, check out

(DGHCX)

Dresdner RCM Global Health Care. If you don't mind paying a 3% maximum

front-end load, or sales charge, check out

(FBIOX) - Get Report

Fidelity Select Biotechnology -- the firm's sector funds are typically strong performers thanks to its strong bench of analysts. If you work with a broker, check out broker-sold

(ETHSX) - Get Report

Eaton Vance Worldwide Health Sciences -- broker-sold

(FBDIX) - Get Report

Franklin Biotech Discovery fund is closed to new investors.

But keep in mind that the mercurial sector is due to cool -- making these funds a potentially risky bet. After all, between 1993 and 1996 the Amex Biotech Index lost 3.3%.

A look at the cumulative top-10 holdings of these leading funds shows their biotech focus. All 10 stocks are either classified as biotech or pharmaceutical shops and include none of the industry giants like

Merck

(MRK) - Get Report

,

Pfizer

(PFE) - Get Report

or

Bristol-Myers Squibb

(BMY) - Get Report

.

If you're looking for a broader health care fund you have options, but not at the top of the charts. Perhaps the best is

(VGHCX) - Get Report

Vanguard Health Care -- the $16.7 billion no-load fund run by guru Ed Owens. Despite the fund's girth it has a solid track record. During the past three-, five- and 10-year periods the fund beat more than 75% of its peers.

Another option is the

(FSPHX) - Get Report

Fidelity Select Health Care fund, which carries a maximum 3% sales charge. Here you get access to

Fidelity's

research acumen but with a broader portfolio of health care stocks.

If you work with a broker, you might check out

(PHSTX) - Get Report

Putnam Health Sciences Trust and

(MAHCX)

Merrill Lynch Healthcare, two broker-sold funds with broad portfolios that have lagged their biotech-fed peers over the past couple of years.