Plasma fibrinogen concentration is a risk factor for cardiovascular disease and has become a common component of epidemiologic studies. Also, fibrinogen analysis has become an important component of clinical trials of thrombolytic therapy and anticoagulation. We studied fibrinogen values from plasma containing three different anticoagulants and compared two different instruments. Clot-rate assays were performed on plasma containing sodium citrate (the recommended specimen) as well as ethylenediamine-tetraacetic acid (EDTA) and EDTA plus D-Phe-Pro-Arg chloromethyl ketone (PPACK) and aprotinin (special anticoagulant), specimens often obtained in multicenter studies. We compared a fibrometer (the BBL) with an analyzer (the Diagnostica Stago ST4), which offers improved throughput, ease of use, and precision. The correlation of citrate and EDTA fibrinogen values (fibrometer) was r = .9718; for citrate and special anticoagulant plasma, r = .9717. Correlations of fibrinogen values from the fibrometer and the analyzer were r = .9558 and r = .9857 for citrate samples and special anticoagulant samples, respectively. We conclude that (1) fibrinogen may be measured by clot-rate assay in EDTA-containing samples and that values may be compared with values obtained from citrate plasma with a correction; (2) samples containing PPACK may be used with only slight modification of the method; and (3) values obtained on the analyzer are directly comparable with those obtained on the fibrometer, facilitating large studies.