  We present recent near-infrared detections of circumstellar disks around the
two old PMS Herbig stars HD 141569 and HD 100546 obtained with the HST/NICMOS2
camera. They reveal extended structures larger than 350-400 AU in radius. While
the HD 100546 disk appears as a continuous disk down to 40 AU, the HD 141569
environment seems more complex, splitted at least into two dust populations. As
a convincing example, the full modeling of the disk surrounding HR 4796,
another old PMS star, is detailed and confronted with more recent observations.
