To test the hypothesis of a sex-linked factor influencing the occurrence of alcoholism and alcohol abuse, alcoholism or abuse rates were compared for 136 sons of the sons vs 134 sons of the daughters of 75 alcoholics. No substantial difference between the groups of grandsons was found in frequency of officially registered alcoholism or alcohol abuse, or both, which suggests no sex-linked factor is involved. The total sample was also used to calculate the risk of such registration for the grandson; the rate of registration by the grandsons' fifth decade of life was 43%, approximately three times that of the general male population, and even higher than the equivalent rate in brothers of alcoholics. This result is incompatible with an assumption of a recessive gene being involved in the occurrence of alcoholism, though it fits with the assumption of a dominant gene.