Rapid measurements of in vivo proton spin-lattice relaxation times (T1) in human tissues were performed by magnetic resonance imaging in a 1.5 T whole-body super-conducting MR scanner. The measurements employ serial TurboFLASH imaging (Snapshot-FLASH) with scan times for a single experiment below 4 s. Using centric phase encoding order, an appropriate fitting of the T1-parameter from images with minimum motion artifacts is possible. Comparative T1-determination with a multipoint inversion recovery and spin-echo technique was performed on phantoms containing Gd-DTPA solutions with different T1-values. We found a maximum deviation of 3.3% for T1 < 1100 ms and of 12.1% for 1100 ms < T1 < 1700 ms from the results obtained by the IR technique. In vivo measurements of T1-relaxation times were performed in white and grey matter, cerebrospinal fluid, kidney, liver, spleen, muscle, and bone marrow, and yielded values that are in good agreement with reported data.