Although glucose is regularly administered to patients after partial hepatic resection, its contribution to survival and/or liver regeneration is unclear. To examine this question fed and anesthetized rats underwent 68% or 90% hepatectomy and received either oral 20% glucose solution or tap water (controls) ad lib for 24 h. Survival was compared by life table analysis and the regeneration response measured by 3H-thymidine uptake into liver deoxyribonucleic acid (DNA). Profound hypoglycemia (60 +/- 8 mg/dl) following 90% hepatectomy in controls was corrected by glucose feeding (99 +/- 25 mg/dl) and survival was enhanced (75 +/- 0.09% vs. 42 +/- 0.1%, p less than 0.01). No deaths occurred in the 68% hepatectomy groups wherein untreated hypoglycemia was not as severe (106 +/- 6 mg/dl). However, after 68% hepatectomy glucose adversely affected the regeneration response. We conclude that glucose feeding corrected the life threatening hypoglycemia following 90% hepatectomy. Prophylactic glucose administration after 68% hepatectomy reduced the liver regeneration response. Selective glucose administration to prevent lethal hypoglycemia may provide optimal survival and conditions for regeneration.