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 break down some of the mutual funds with the top Zacks Mutual Fund Rank and the lowest fees.

Wells Fargo Large Cap Growth R6 (STFFX Quick QuoteSTFFX - Free Report) : 0.74% expense ratio and 0.68% management fee. STFFX 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 annual returns of 11.06% over the last five years, this fund is a winner.

Matthews China Small Companies Investor (MCSMX Quick QuoteMCSMX - Free Report) . Expense ratio: 1.43%. Management fee: 1%. MCSMX is a Pacific Rim - Equity fund, which usually invest in companies with a big presence in the export-focused markets of Hong Kong, Singapore, Taiwan, and Korea. This fund has managed to produce a robust 9.48% over the last five years.

Ivy Mid Cap Growth A (WMGAX Quick QuoteWMGAX - Free Report) is an attractive large-cap allocation. WMGAX is a Mid Cap Growth mutual fund. These mutual funds choose companies with a stock market valuation between $2 billion and $10 billion. WMGAX has an expense ratio of 1.12%, management fee of 0.77%, and annual returns of 13.5% 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.