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.

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 investors' portfolios.

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

If you are looking to diversify your portfolio, consider Fidelity Advisor Biotechnology M (FBTTX). FBTTX is a Sector - Health mutual fund, which give investors an opportunity to focus on healthcare, one of the largest sectors of the American economy. This fund is a winner, boasting an expense ratio of 1.19%, management fee of 0.69%, and a five-year annualized return track record of 12.3%.

BlackRock Advantage Lrg Cap Gr K (BMCKX Quick QuoteBMCKX - Free Report) . Expense ratio: 0.57%. Management fee: 0.56%. BMCKX 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. This fund has managed to produce a robust 12.85% over the last five years.

TETON Westwood Small Cap Equity A (WWSAX): 1.25% expense ratio and 1% management fee. WWSAX is a Small Cap Blend mutual fund, allowing investors a way to diversify their funds among various types of small-cap stocks. The fund is mainly invested in equities, has a long reputation of salutary performance, and has yearly returns of 12.32% over the last five years.

There you have it. If your financial advisor had you put your money into any of our top-ranked funds, then they've got you covered. If not, you may need to talk.