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

Commerce Growth Fund (CFGRX Quick QuoteCFGRX - Free Report) : 0.71% expense ratio and 0.4% management fee. CFGRX 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 annual returns of 16.22% over the last five years, this fund is a winner.

Fidelity Fund K (FFDKX Quick QuoteFFDKX - Free Report) is a stand out amongst its peers. FFDKX is a Large Cap Blend fund, targeting companies with market caps of over $10 billion. These funds offer investors a stability, and are perfect for people with a "buy and hold" mindset. With five-year annualized performance of 17.14%, expense ratio of 0.37% and management fee of 0.32%, this diversified fund is an attractive buy with a strong history of performance.

Queens Road Small Cap Value Fund (QRSVX Quick QuoteQRSVX - Free Report) : 0.98% expense ratio and 0.66% management fee. QRSVX is a Small Cap Value mutual fund, investing in small companies with stock market valuation less than $2 billion. With a five-year annual return of 11.09%, this fund is a well-diversified fund with a long track record of success.

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.