The blue crab Callinectes sapidus is an ecologically and economically important component of marine and estuarine ecosystems of the western Atlantic and Gulf of Mexico. Current stock assessments lack a clear understanding of the age structure of blue crab populations in Florida (USA). Blue crabs and other crustaceans are especially difficult to age because of the complex nature of their discrete, rather than continuous, growth patterns. Chesapeake Bay researchers developed a method of aging blue crabs by assaying the aging pigment lipofuscin extracted from eyestalk nerve tissue. Here we investigated the usefulness of that method in determining the age of blue crabs inhabiting Florida waters. Assays of a wild-caught, young-of-the-year cohort that was pond-raised revealed a negative linear trend in lipofuscin indices over an 18 mo culture period. Assays of a tank-raised cohort of captive-bred crabs of known age also showed no relationship between the lipofuscin index and age over an 11 mo period. These results suggest that lipofuscin assays, as used in the Chesapeake Bay populations, are not useful in determining the age of blue crabs in Florida waters. Further study is warranted to determine how the procedure might be modified for Florida blue crab populations.