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 take a look at some of our top-ranked mutual funds with the lowest fees.

If you are looking to diversify your portfolio, consider Congress Large Cap Growth Fund (CAMLX Quick QuoteCAMLX - Free Report) . CAMLX is a Large Cap Growth mutual fund, and these funds invest in many large U.S. firms that are projected to grow at a faster rate than their large-cap peers. This fund is a winner, boasting an expense ratio of 0.94%, management fee of 0.5%, and a five-year annualized return track record of 17.04%.

T. Rowe Price Mid-Cap Growth R (RRMGX Quick QuoteRRMGX - Free Report) is a stand out amongst its peers. RRMGX is a Mid Cap Growth mutual fund. These mutual funds choose companies with a stock market valuation between $2 billion and $10 billion. With five-year annualized performance of 11.22%, expense ratio of 1.29% and management fee of 0.61%, this diversified fund is an attractive buy with a strong history of performance.

Vanguard Explorer Fund Investor (VEXPX Quick QuoteVEXPX - Free Report) : 0.46% expense ratio and 0.44% management fee. VEXPX is a Small Cap Growth mutual fund and tends to feature small companies in up-and-coming industries and markets. With a five-year annual return of 13%, this fund is a well-diversified fund with a long track record of success.

There you have it. If your financial advisor had you put your money into any of our top-ranked funds, then they've got you covered. If not, you may need to talk.