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.

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

AllianzGI Mid-Cap Fund Institutional

(DRMCX Quick QuoteDRMCX - Free Report) : 0.77% expense ratio and 0.47% management fee. DRMCX is a Mid Cap Growth mutual fund. These funds aim to target companies with a market capitalization between $2 billion and $10 billion that are also expected to exhibit more extensive growth opportunities for investors than their peers. DRMCX has achieved five-year annual returns of an astounding 11.31%.

RMB Smid Cap I

(RMBMX Quick QuoteRMBMX - Free Report) . Expense ratio: 0.8%. Management fee: 0.7%. RMBMX 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. This fund has managed to produce a robust 12.23% over the last five years.

Northern Large Cap Core

(NOLCX Quick QuoteNOLCX - Free Report) : 0.45% expense ratio and 0.44% management fee. NOLCX 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. The fund is mainly invested in equities, has a long reputation of salutary performance, and has yearly returns of 14.96% 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.