A secondary structure has been predicted for the C termini of the fibrinogen beta and gamma chains from an aligned set of homologous protein sequences using a transparent method that extracts conformational information from patterns of variation and conservation, parsing strings, and patterns of amphiphilicity. The structure is modeled to form two domains, the first having a core parallel sheet flanked on one side by at least two helices and on the other by an antiparallel amphiphilic sheet, with an additional helix connecting the two sheets. The second domain is built entirely from beta strands.