The effect of ethylene on tuber sprout growth and quality in potato (Solanum tuberosum L. 'Russet Burbank') was tested in laboratory and commercial studies for 6 and 3 years respectively, in comparison with untreated (laboratory study) and CIPC-treated tubers (laboratory and commercial studies). In both studies, ethylene was applied continuously at 166 micromoles.m-1 for at least 25 weeks, beginning in early December (laboratory study) or early December to early January (commercial study). In the laboratory study, ethylene delayed the appearance of sprouts for 5 to 15 weeks, compared with untreated tubers. In the ethylene-treated tubers in both studies, sprouts appeared on many eyes but most of them remined very small (5 mm long). Longer sprouts (5 mm) appeared after 15 weeks but did not exceed 12 and 59 mm in the laboratory and commercial studies, respectively. Sprouts on ethylene-treated tubers were more easily detached up to 6 weeks after ethylene treatment ended, compared with untreated tubers. In both studies, ethylene treatment was not associated with decay, disorder or internal sprouting problems. In both studies, the Agtron fry color [or US. Dept. of Agriculture (USDA) color grade] of ethylene-treated tubers was darker than CIPC-treated tubers at almost all sampling times. Continuous exposure to ethylene was an effective sprout control agent but it produced a darker fry color, compared with CIPC-treated potatoes