The Northeast Marine Fisheries Board recently completed a comprehensive management plan for American lobster Homarus americanus, the most important provision of which is to raise the legal minimum size of lobsters from 81 to 88.9 mm carapace length incrementally over 5 years. Its objective is to increase egg production and recruitment, and thus reduce the likelihood of stock failure; economic benefits are anticipated for fishermen. However, a model used to analyze the frequency distributions of some 9,000 Maine lobsters demonstrates that in every year the legal minimum size is increased, smaller numbers and less weight of lobsters would be landed than at present. After the legal measure reaches 88.9 mm, there most likely still would be fewer lobsters harvested, but a 7.9% increase in landed weight due to increases in yield/recruit. An economic analysis by two-stage least-squares regression demonstrates that these changes in catches would result in a loss in total revenue to the Maine lobster industry in all 5 years the legal measure is increased. After it has reached 88.9 mm, total revenue to lobster fishermen most likely would be 5.5% higher than it is now, a 13% internal rate of return on investment. These results suggest that increasing the legal lobster measure is problematic from the point of view of those in the industry.