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 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.

Fidelity Advisor Technology I has a 0.72% expense ratio and 0.52% management fee. With a much more diversified approach, FATIX--part of the Sector - Tech mutual fund category--gives investors a way to own a stake in the notoriously risky tech sector. With yearly returns of 18.92% over the last five years, this fund clearly wins.

Janus Henderson Global Life Science S (JFNSX Quick QuoteJFNSX - Free Report) : 1.18% expense ratio and 0.64% management fee. JFNSX 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 yearly returns of 8.33% over the last five years, JFNSX is an effectively diversified fund with a long reputation of solidly positive performance.

Principal Mid Cap R1 : 1.47% expense ratio and 0.58% management fee. PMSBX 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. The fund is mainly invested in equities, has a long reputation of salutary performance, and has yearly returns of 9.33% 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.