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

MassMutual Premier Disciplined Growth Service Class (DEIGX Quick QuoteDEIGX - Free Report) has a 0.78% expense ratio and 0.45% management fee. DEIGX 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 10.48% over the last five years, this fund clearly wins.

Fidelity Series Growth & Income (FGLGX Quick QuoteFGLGX - Free Report) . Expense ratio: 0.63%. Management fee: 0%. FGLGX is part of the Large Cap Blend section, and these mutual funds most often invest in firms with a market capitalization of $10 billion or more. By investing in bigger companies, these funds offer more stability, and are often well-suited for investors with a "buy and hold" mindset. This fund has managed to produce a robust 11.5% over the last five years.

Hennessy Cornerstone Mid Cap 30 Investor (HFMDX Quick QuoteHFMDX - Free Report) . Expense ratio: 1.35%. Management fee: 0.74%. Five year annual return: 9.68%. HFMDX is a Mid Cap Blend mutual fund, and usually features a portfolio with stocks of various styles and sizes, allowing for diversification within a strategy that focuses on mid cap companies.

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.