High-throughput ballistic injection nanorheology is a method for the quantitative study of cell mechanics. Ccell mechanics are measured by ballistic injection of submicron particles into the cytoplasm of living cells and tracking the spontaneous displacement of the particles at high spatial resolution. Tthe trajectories of the cytoplasm-embedded particles are transformed into mean-squared displacements, which are subsequently transformed into frequency-dependent viscoelastic moduli and time-dependent creep compliance of the cytoplasm. Tthis method allows for the study of a wide range of cellular conditions, including cells inside a 3D matrix, cell subjected to shear flows and biochemical stimuli, and cells in a live animal. Ballistic injection lasts < 1 min and is followed by overnight incubation. Multiple particle tracking for one cell lasts < 1 min. Forty cells can be examined in < 1 h.