  We present the first results of the treatment of grain growth in our 3D,
two-fluid (gas+dust) SPH code describing protoplanetary disks. We implement a
scheme able to reproduce the variation of grain sizes caused by a variety of
physical processes and test it with the analytical expression of grain growth
given by Stepinski & Valageas (1997) in simulations of a typical T Tauri disk
around a one solar mass star. The results are in agreement with a turbulent
growing process and validate the method. We are now able to simulate the grain
growth process in a protoplanetary disk given by a more realistic physical
description, currently under development. We discuss the implications of the
combined effect of grain growth and dust vertical settling and radial migration
on subsequent planetesimal formation.
