There is never a wrong time to invest in mutual funds for retirement. So, if you're still looking for the best mutual funds, the Zacks Mutual Fund Rank can be a great guide.

The best way to shortlist great mutual funds is to ensure solid performance, diversification, and low fees. Some are better than others, but utilizing the Zacks Mutual Fund Rank, we have identified three mutual funds that could be solid additions to one's retirement portfolio.

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

Fidelity Growth & Income Portfolio

(FGRIX Quick QuoteFGRIX - Free Report) has a 0.57% expense ratio and 0.43% management fee. FGRIX 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 yearly returns of 14.62% over the last five years, this fund clearly wins.

MFS Mid Cap Value Fund I

(MCVIX Quick QuoteMCVIX - Free Report) : 0.74% expense ratio and 0.61% management fee. MCVIX is a Mid Cap Value fund, which usually invests in companies with a stock market valuation between $2 billion and $10 billion. With yearly returns of 11.42% over the last five years, MCVIX is an effectively diversified fund with a long reputation of solidly positive performance.

TIAA-CREF Large Cap Value Premier

(TRCPX Quick QuoteTRCPX - Free Report) : 0.56% expense ratio and 0.4% management fee. TRCPX 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. With a five-year annual return of 11.45%, 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.