It is never too late to invest in mutual funds for retirement. As such, if you plan to invest in some of the best funds, the Zacks Mutual Fund Rank can provide you with valuable guidance.

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.

SEI Inst Mgd Tr-Small Cap Value F (SESVX): 1.1% expense ratio and 0.65% management fee. SESVX is a Small Cap Value mutual fund option, which typically invest in companies with market caps under $2 billion. SESVX has achieved five-year annual returns of an astounding 10.04%.

JPMorgan US GARP Equity A (JIGAX Quick QuoteJIGAX - Free Report) : 0.84% expense ratio and 0.3% management fee. JIGAX 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 16.28% over the last five years, JIGAX is an effectively diversified fund with a long reputation of solidly positive performance.

Putnam Large Cap Value R (PEQRX) is an attractive large-cap allocation. PEQRX 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. PEQRX has an expense ratio of 0.56%, management fee of 0.46%, and annual returns of 14.89% 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.