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.

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

Thrivent Large Cap Value Fund A (AAUTX Quick QuoteAAUTX - Free Report) : 0.85% expense ratio and 0.45% management fee. AAUTX 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. AAUTX has achieved five-year annual returns of an astounding 11.29%.

Fidelity Advisor Equity Growth Z (FZAFX Quick QuoteFZAFX - Free Report) : 0.59% expense ratio and 0.52% management fee. FZAFX 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. FZAFX, with annual returns of 19.84% over the last five years, is a well-diversified fund with a long track record of success.

Principal Mid Cap J (PMBJX Quick QuotePMBJX - Free Report) : 0.8% expense ratio and 0.58% management fee. PMBJX is a Mid Cap Growth mutual fund. These funds aim to target companies with a market capitalization between $2 billion and $10 billion that are also expected to exhibit more extensive growth opportunities for investors than their peers. The fund is mainly invested in equities, has a long reputation of salutary performance, and has yearly returns of 11.03% over the last five years.

We hope that your investment advisor (if you use one) has you invested in one or all of the top-ranked mutual funds we've reviewed. But if that isn't the case, it might be time to have a conversation or reconsider this vitally important relationship.