It is never too late to invest in mutual funds for retirement. As such, if you plan to invest in some of the best funds, the Zacks Mutual Fund Rank can provide you with valuable guidance.

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.

Eaton Vance Emg & Frontr Cntrys I (EICOX Quick QuoteEICOX - Free Report) : 1.15% expense ratio and 0.98% management fee. EICOX is a part of the Non US - Equity fund category, many of which will focus across all cap levels, and will typically allocate their investments between emerging and developed markets. EICOX has achieved five-year annual returns of an astounding 16.15%.

PIMCO Dividend & Income Institutional (PQIIX). Expense ratio: 0.7%. Management fee: 0.69%. PQIIX is classified as an Allocation Balanced fund, which seeks to invest in a balance of asset types, like stocks, bonds, and cash, and including precious metals or commodities is not unusual. This fund has managed to produce a robust 11.89% over the last five years.

Undiscovered Managers Behavioral Value I (UBVSX): 0.98% expense ratio and 0.75% management fee. UBVSX is a Small Cap Value mutual fund option, which typically invest in companies with market caps under $2 billion. With a five-year annual return of 18.98%, 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.