The changing ability of seed and embryo parts of Pinus palustris Mill. and P. elliottii Engelm. to use alcohol, a product of anaerobic respiration, was studied during germination and early seedling development. From the start of germination to the 10 to 12th day, alcohol dehydrogenase (ADH) activity increased slowly in the embryos of both species. Then, as radicles emerged, activity more than doubled. Thereafter, as epicotyl emergence was completed during the next 10 days, ADH activity declined almost to zero. Highest activity was noted in the elongating portions of the radicles and epicotyls. Only after the seedlings of the two species were approaching self-sufficiency was there an indication of ADH activity in megagametophyte tissue.