Fast spin-echo (FSE) pulse sequences enable T2-weighted imaging in a fraction of the time required for T2-weighted conventional spin-echo (CSE) imaging. Due to concerns that the altered contrast characteristics of FSE may interfere with the visualization of multiple sclerosis (MS) lesions, the sensitivity of T2-weighted FSE sequences was compared to comparably weighted CSE sequences in the imaging of the brain in 100 patients with clinically suspected MS. The proton-density FSE sequence revealed more MS lesions than its CSE counterpart, while the T2-weighted CSE sequences were found to be more sensitive than the T2-weighted FSE sequence. Contrast-to-noise ratios and signal-to-noise ratios compared favorably between sequences. Overall, there was little difference in the specificity between FSE and CSE in the diagnosis of MS. The higher sensitivity and the reduction in time attainable through the use of FSE warrants its replacement of CSE when imaging the brain in patients with clinically suspected MS. J. Magn. Reson. Imaging 2001;13:657-667.