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.

How can you tell a good mutual fund from a bad one? It's pretty basic: if the fund is diversified, has low fees, and shows strong performance, it's a keeper. Of course, there's a wide range, but using the Zacks Mutual Fund Rank, we've found three mutual funds that would be great additions to any long-term investors' portfolios.

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

MFS Blended Research Intl Eq R6 (BRXVX): 0.57% expense ratio and 0.35% management fee. BRXVX is a Non US - Equity option, focusing their investments acoss emerging and developed markets, and can often extend across cap levels too. With annual returns of 11.12% over the last five years, this fund is a winner.

Federated MDT Stock Trust IS (FMSTX): 0.76% expense ratio and 0.65% management fee. FMSTX is a Large Cap Value fund. These funds invest in stocks with a market cap of $10 billion of more, but whose share prices do not reflect their intrinsic value. FMSTX, with annual returns of 13.31% over the last five years, is a well-diversified fund with a long track record of success.

Alger 35 Z (ATVPX Quick QuoteATVPX - Free Report) : 0.56% expense ratio and 0.45% management fee. ATVPX is a Large Cap Growth option; these mutual funds purchase stakes in numerous large U.S. companies that are expected to develop and grow at a faster rate than other large-cap stocks. With a five-year annual return of 10.77%, 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.