¶1 This is an appeal from a judgment entered by the Superior Court of Screven County granting summary judgment in favor of the defendants. Plaintiff-appellant, an heir-at-law of testator, filed a caveat to her father’s will on the grounds that (a) decedent was of unsound mind at execution of the will and (b) the decedent was under the undue influence of his son at the time of the making of the will. Appellees (co-executors) moved for summary judgment, supported by an affidavit executed by two witnesses to the will and affidavits executed by the two appellees, which stated that in their opinion the will was voluntary and the product of a sound mind not subject to any undue influence. Appellant’s testimonial evidence consisted of her verified petition for a caveat and a counter-affidavit alleging facts intended to prove the contentions in her petition.
¶2 Appellant contends that the question of undue *404 influence and testamentary capacity is a question of fact for the jury. We agree. On a motion for summary judgment the burden of establishing the non-existence of any genuine issue of fact is upon the moving party and all doubts are to be resolved against the movant. Ham v. Ham, 230 Ga. 43, 45 (195 SE2d 429). This is true even as to issues upon which the opposing party would have the trial burden. Ibid. While opinion evidence will make a jury issue, it will not authorize the grant of a summary judgment. Ehlers v. Golding, 227 Ga. 742 (182 SE2d 870); Harrison v. Tuggle, 225 Ga. 211, 213 (167 SE2d 395).
¶3 The trial court erred in granting defendants’ motion for summary judgment.
¶4 Judgment reversed.