We have reanalyzed the statistics on uterine weights used by Virgo in his article, The Estrogenicity of Delta-9-Tetrahydrocannabinol (THC): THC Neither Blocks nor Induces Ovum Implantation, nor does it Effect Uterine Growth, which appeared in Res. Comm. Chem. Path. and Pharmacol. 25:65-77 (1979). The reanalysis shows that administration of 3 and 6 mg/kg delta 9 THC to ovariectomized mice results in highly significant (P < .002; P < .0001 respectively) increases in uterine weights. These data are in accord with the uterotrophic effect of delta 9 THC observed in ovariectomized rats.