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 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.

Fidelity Select Pharmaceuticals

(FPHAX Quick QuoteFPHAX - Free Report) : 0.74% expense ratio and 0.69% management fee. FPHAX is classified as a Sector - Health fund. Healthcare is one of the biggest sectors of the American economy, and these kinds of mutual funds provide a great opportunity to invest in this industry. With annual returns of 16.83% over the last five years, this fund is a winner.

T. Rowe Price Financial Services

(PRISX Quick QuotePRISX - Free Report) : 0.83% expense ratio and 0.64% management fee. PRISX is a Sector - Finance mutual fund option, which provide investors with a diversified and stabilized investment approach focused on the financial space, which is a notoriously large, complex, and heavily-regulated industry. With yearly returns of 14.71% over the last five years, PRISX is an effectively diversified fund with a long reputation of solidly positive performance.

TIAA-CREF Growth & Income Premier

(TRPGX Quick QuoteTRPGX - Free Report) is an attractive large-cap allocation. TRPGX 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. TRPGX has an expense ratio of 0.55%, management fee of 0.4%, and annual returns of 16.02% over the past 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.