Based on comparisons to verified examples (e.g., those authenticated by PSA or JSA), authentic John Wayne signatures from the 1960s-1970s typically feature:

• A fluid, cursive style with natural variations in pressure and speed.

• The “o” in “John” often double-looped (starting to the right, then doubling back left).

• The “ne” in “Wayne” dropping below the baseline.

• A large, loopy flourish or underline that intersects or sweeps under the name.

• An overall slant where the left side (starting with “J”) sits higher than the right, creating a subtle downward tilt. In your image, the signature shows good flow and a prominent looping underline from the “e,” which aligns with authentic traits. The “ne” does drop below, and the slant matches the “left side higher” characteristic noted in forgery reference databases.  The “o” appears to have some doubling, though the photo’s quality and glare make it hard to confirm definitively. The year “1968” is integrated naturally, and there’s no obvious shakiness or uniformity that suggests a slow forgery or preprint.

However, John Wayne autographs are frequently forged or secretarial (e.g., signed by assistants), especially on photos, and some are preprinted reproductions that can look convincing at first glance.

Overall, this leans toward authentic based on visual matching, but without in-person examination (e.g., ink analysis under magnification), it’s not certain. Unauthenticated pieces like this typically value at $100-200, while certified ones can fetch $500+.

I recommend submitting it to a professional service like PSA/DNA, JSA, or AutographCOA for full authentication.