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.

How can you tell a good mutual fund from a bad one? It's pretty basic: if the fund is diversified, has low fees, and shows strong performance, it's a keeper. Of course, there's a wide range, but using the Zacks Mutual Fund Rank, we've found three mutual funds that would be great additions to any long-term retirement investors' portfolios.

Let's learn about some of Zacks' highest ranked mutual funds with low fees you may want to consider.

Frost Growth Equity Institutional (FICEX Quick QuoteFICEX - Free Report) : 0.63% expense ratio and 0.5% management fee. FICEX is a Large Cap Growth mutual fund, and these funds invest in many large U.S. firms that are projected to grow at a faster rate than their large-cap peers. With annual returns of 11.78% over the last five years, this fund is a winner.

Goldman Sachs Blue Chip US Equity Investor (GIRGX Quick QuoteGIRGX - Free Report) is a stand out amongst its peers. GIRGX is a Large Cap Blend fund, targeting companies with market caps of over $10 billion. These funds offer investors a stability, and are perfect for people with a "buy and hold" mindset. With five-year annualized performance of 10.67%, expense ratio of 0.79% and management fee of 0.55%, this diversified fund is an attractive buy with a strong history of performance.

Janus Henderson Global Life Science T (JAGLX Quick QuoteJAGLX - Free Report) : 0.9% expense ratio and 0.64% management fee. JAGLX is part of the Sector - Health category, offering investors a focus on the healthcare industry, one of the largest sectors in the American economy. With a five-year annual return of 8.63%, this fund is a well-diversified fund with a long track record of success.

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.