Investing in mutual funds for retirement is never too late. And the Zacks Mutual Fund Rank can be an excellent tool for investors looking to invest in the best funds.

The easiest, most reliable way to judge a mutual fund's quality over time is by analyzing its performance, diversification, and fees. The Zacks Mutual Fund Rank, which covers over 19,000 mutual funds, has helped us identify three outstanding options that are perfect for any long-term investors' portfolios that is retirement-focused.

Let's learn about some of Zacks' highest ranked mutual funds with low fees you may want to consider.

Fidelity Select Pharmaceuticals (FPHAX Quick QuoteFPHAX - Free Report) : 0.73% expense ratio and 0.53% management fee. FPHAX is part of the Sector - Health category, offering investors a focus on the healthcare industry, one of the largest sectors in the American economy. FPHAX has achieved five-year annual returns of an astounding 13.48%.

BlackRock Advantage Large Cap Value I (MALVX Quick QuoteMALVX - Free Report) is a stand out amongst its peers. MALVX is a Large Cap Value mutual fund, which invests in stocks with a market cap of $10 billion of more, but whose share prices do not reflect their intrinsic value. With five-year annualized performance of 9.62%, expense ratio of 0.54% and management fee of 0.49%, this diversified fund is an attractive buy with a strong history of performance.

T. Rowe Price US Equity Research (PRCOX Quick QuotePRCOX - Free Report) : 0.44% expense ratio and 0.33% management fee. PRCOX is a Large Cap Blend fund, targeting companies with market caps of over $10 billion. These funds offer investors a stability, and are perfect for people with a "buy and hold" mindset. With a five-year annual return of 15.64%, this fund is a well-diversified fund with a long track record of success.

These examples highlight the fact that there are some astonishingly good mutual funds out there. If your advisor has you in the good ones, bravo! If not, you may need to have a talk.