We discuss quantum fluctuations of a class of rotating strings in AdS5xS5. In particular, we develop a systematic method to compute the one-loop sigma-model effective actions in closed forms for large angular momenta. As examples, we explicitly evaluate the leading terms for the constant radii strings in the SO(6) sector with two equal angular momenta, the SU(2) sector, and the SL(2) sector. We also obtain the leading quantum corrections to the space-time energy for these sectors.