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 take a look at some of our top-ranked mutual funds with the lowest fees.

T. Rowe Price Value Adviser (PAVLX Quick QuotePAVLX - Free Report) : 0.95% expense ratio and 0.56% management fee. PAVLX is a Large Cap Value mutual fund, which invests in stocks with a market cap of $10 billion of more, but whose share prices do not reflect their intrinsic value. PAVLX has achieved five-year annual returns of an astounding 12.06%.

Principal Large Cap Growth I A (PLGAX Quick QuotePLGAX - Free Report) : 1% expense ratio and 0.6% management fee. PLGAX 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 yearly returns of 14.01% over the last five years, PLGAX is an effectively diversified fund with a long reputation of solidly positive performance.

Vericimetry U.S. Small Cap Value Fund (VYSVX Quick QuoteVYSVX - Free Report) : 0.6% expense ratio and 0.5% management fee. VYSVX is a Small Cap Value fund, and these funds are known for investing in companies with market caps under $2 billion. With a five-year annual return of 12.04%, 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.