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

Pioneer International Value Y (INVYX Quick QuoteINVYX - Free Report) : 0.7% expense ratio and 0.65% management fee. INVYX is a Non US - Equity option, focusing their investments acoss emerging and developed markets, and can often extend across cap levels too. INVYX has achieved five-year annual returns of an astounding 8.76%.

JPMorgan Intrepid Value Fund R2 (JIVZX Quick QuoteJIVZX - Free Report) : 1.09% expense ratio and 0.3% management fee. JIVZX is a part of the Large Cap Value category, and invests in equities with a market capitalization of $10 billion or more, but whose share prices do not reflect their intrinsic value. With yearly returns of 8.91% over the last five years, JIVZX is an effectively diversified fund with a long reputation of solidly positive performance.

TIAA-CREF Large Cap Growth Retirement (TILRX Quick QuoteTILRX - Free Report) is an attractive large-cap allocation. TILRX 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. TILRX has an expense ratio of 0.65%, management fee of 0.4%, and annual returns of 13.3% 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.