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 way to judge a mutual fund's quality over time is by analyzing its performance, diversification, and fees. Using the Zacks Mutual Fund Rank of over 19,000 mutual funds, we've identified three outstanding mutual funds that are ideally suited to help long-term investors pursue and achieve their retirement investing goals.

Let's break down some of the mutual funds with the top Zacks Mutual Fund Rank and the lowest fees.

Boston US Equity Fund (BTEFX Quick QuoteBTEFX - Free Report) : 0.86% expense ratio and 0.75% management fee. BTEFX is a part of the Large Cap Growth mutual fund category, which invest in many large U.S. companies that are expected to grow much faster compared to other large-cap stocks. BTEFX has achieved five-year annual returns of an astounding 11.46%.

Columbia Dividend Income Fund R5 (CDDRX Quick QuoteCDDRX - Free Report) . Expense ratio: 0.6%. Management fee: 0.53%. CDDRX 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. This fund has managed to produce a robust 9.62% over the last five years.

Oppenheimer Discovery I (ODIIX Quick QuoteODIIX - Free Report) : 0.66% expense ratio and 0.6% management fee. ODIIX is one of many Small Cap Growth mutual funds; these funds tend to create their portfolios around stocks with market capitalization of less than $2 billion. The fund is mainly invested in equities, has a long reputation of salutary performance, and has yearly returns of 8.24% over the last five years.

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.