Measurement of proton transverse relaxation rates (R(2)) is a generally useful means for quantitative characterization of pathological changes in tissue with a variety of clinical applications. The most widely used R(2) measurement method is the Carr-Purcell-Meiboom-Gill (CPMG) pulse sequence but its relatively long scan time requires respiratory gating for chest or body MRI, rendering this approach impractical for comprehensive assessment within a clinically-acceptable examination time. The purpose of our study was to develop a breathhold multiecho fast spin-echo (FSE) sequence for accurate measurement of R(2) in the liver and heart. Phantom experiments and studies of subjects in vivo were performed to compare the FSE data with the corresponding even-echo CPMG data. For pooled data, the R(2) measurements were strongly correlated (Pearson correlation coefficient = 0.99) and in excellent agreement (mean difference [CPMG - FSE] = 0.10 s(-1); 95% limits of agreement were 1.98 and -1.78 s(-1)) between the two pulse sequences.