Abstract: Nanonized formulations of testosterone esters, especially testosterone undecanoate, and of testosterone are prepared which show an enhanced oral bioavailability compared to the existing oral products on the market. The drug is dissolved in a melted lipid phase, which is subsequently nanonized. The drug is associated with the lipid. The drug can also be nanonized without having lipid present yielding nanocrystals. The nanonized drug can be incorporated into tablets or capsules for oral administration, typically one unit is sufficient for delivery of a single dose.