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.

Goldman Sachs US Equity Dividend & Premier IR (GVIRX Quick QuoteGVIRX - Free Report) : 0.78% expense ratio and 0.7% management fee. GVIRX 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. GVIRX has achieved five-year annual returns of an astounding 12.58%.

RBC SMID Cap Growth I (TMCIX Quick QuoteTMCIX - Free Report) : 0.82% expense ratio and 0.7% management fee. TMCIX is a Mid Cap Growth mutual fund. These funds aim to target companies with a market capitalization between $2 billion and $10 billion that are also expected to exhibit more extensive growth opportunities for investors than their peers. With yearly returns of 14.35% over the last five years, TMCIX is an effectively diversified fund with a long reputation of solidly positive performance.

T. Rowe Price Mid-Cap Value I (TRMIX Quick QuoteTRMIX - Free Report) . Expense ratio: 0.67%. Management fee: 0.64%. Five year annual return: 13.38%. TRMIX is a Mid Cap Value mutual funds that aims to target medium-sized companies that possess strong value and income opportunities for investors.

These examples highlight the fact that there are some astonishingly good mutual funds out there. If your advisor has you in the good ones, bravo! If not, you may need to have a talk.