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.

Boston Partners Global Equity Institutional (BPGIX Quick QuoteBPGIX - Free Report) : 0.95% expense ratio and 0.9% management fee. BPGIX is a Global - Equity mutual fund, which invests their assets in large markets, leveraging the global economy. BPGIX has achieved five-year annual returns of an astounding 17.3%.

Federated International Leaders IS (FGFLX). Expense ratio: 0.78%. Management fee: 0.72%. FGFLX is a Non US - Equity option, focusing their investments acoss emerging and developed markets, and can often extend across cap levels too. This fund has managed to produce a robust 11.43% over the last five years.

T.Rowe Price Integrat US SMID Core (TQSMX): 0.87% expense ratio and 0.63% management fee. TQSMX is a Small Cap Blend mutual fund, and usually targets stocks with market caps of less than $2 billion, letting investors diversify their funds among other kinds of small-cap equities. The fund is mainly invested in equities, has a long reputation of salutary performance, and has yearly returns of 14.33% 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.