Rotating-frame relaxation rates, R_1p, are often measured in NMR studies of protein dynamics. We show here that large systematic errors can be introduced into measured values of heteronuclear R_1p rates using schemes which are usually employed to suppress cross-correlation between dipole-dipole and CSA relaxation mechanisms. For example, in a scalar-coupled two-spin X-H spin system the use of ¹H WALTZ16 decoupling or ¹H pulses applied at regularly spaced intervals leads to a significant overestimation of heteronuclear R_1p values. The problem is studied experimentally and theoretically for ¹⁵N-¹H and ¹³C-¹H spin pairs, and simple schemes are described which eliminate the artifacts. The approaches suggested are essential replacements of existing methodology if accurate dynamics parameters are to be extracted from spin-lock relaxation data sets.