Filed Pursuant to Rule 497(e)

Registration No. 033-10583

THE GAMCO GROWTH FUND

Supplement dated June 12, 2018

to the

Prospectus dated April 30, 2018

This supplement amends certain information in the Prospectus (the “Prospectus”), dated April 30, 2018, of The GAMCO Growth Fund (the “Fund”). Unless otherwise indicated, all other information included in the Prospectus, or any previous supplements thereto, that is not inconsistent with the information set forth in this supplement remains unchanged. Capitalized terms not otherwise defined in this supplement have the same meaning as in the Prospectus.

The following replaces the heading “Morgan Stanley Wealth Management” in Appendix A to the Prospectus:

Morgan Stanley Wealth Management

Effective July 1, 2018, shareholders purchasing Fund shares through a Morgan Stanley Wealth Management transactional brokerage account will be eligible only for the following front-end sales charge waivers with respect to Class A shares, which may differ from and may be more limited than those disclosed elsewhere in this Fund’s Prospectus or SAI.

 

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Employer-sponsored retirement plans (e.g., 401(k) plans, 457 plans, employer-sponsored 403(b) plans, profit sharing and money purchase pension plans and defined benefit plans). For purposes of this provision, employer-sponsored retirement plans do not include SEP IRAs, Simple IRAs, SAR-SEPs or Keogh plans

 

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Morgan Stanley employee and employee-related accounts according to Morgan Stanley’s account linking rules

 

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Shares purchased through reinvestment of dividends and capital gains distributions when purchasing shares of the same fund

 

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Shares purchased through a Morgan Stanley self-directed brokerage account

 

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Class C (i.e., level-load) shares that are no longer subject to a contingent deferred sales charge and are converted to Class A shares of the same fund pursuant to Morgan Stanley Wealth Management’s share class conversion program

 

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Shares purchased from the proceeds of redemptions within the same fund family, provided (i) the repurchase occurs within 90 days following the redemption, (ii) the redemption and purchase occur in the same account, and (iii) redeemed shares were subject to a front-end or deferred sales charge.

Shareholders Should Retain This Supplement For Future Reference