The aim of this study was to evaluate the in-vivo behaviour of matrix pellets formulated with nanocrystalline ketoprofen after oral administration to dogs. No significant differences in AUC-values were seen between pellet formulations containing nanocrystalline or microcrystalline ketoprofen and a commercial ketoprofen formulation (reference: Rofenid 200 Long Acting). C(max) of the formulations containing nano- or microcrystalline ketoprofen was significantly higher compared to reference, whereas t(max) was significantly lower. The in-vivo burst release observed for the spray dried nanocrystalline ketoprofen matrix pellets was reduced following compression of the pellets in combination with placebo wax/starch pellets. These matrix tablets sustained the ketoprofen plasma concentrations during 5.6 and 5.4 h for formulations containing nano- and microcrystalline ketoprofen, respectively.