Using femtosecond two-color resonant, two-photon ionization spectroscopy followed by mass-selective detection, we studied the fragmentation of small neutral sodium clusters in a supersonic cluster beam. The photofragmentation dynamics of the clusters could be investigated with the pump and probe technique. Ultrashort laser pulses of 150-fs duration were employed to excite the sodium clusters. Being predissociated, the prepared clusters tend to ultrafast fragmentation. The temporal behavior of these predissociation processes could be detected by using variably delayed probe pulses to ionize the nonbroken excited clusters. In the frame of a simple energy level model the fragmentation processes could be analyzed. Fragmentation times for the different duster sizes could be estimated to be energy dependent in the region 220-900 fs. The temporal evolution of the ion signals exhibits-as a function of cluster size-an interesting odd-even alternation.