The present work sets forth a numeriacal simulation of the processo f particle deposition in a laminar pipe flow subjected to external heating. The simulation is aimed at modeling the MCVD (Modified Chemical vapor Deposition) process utilized in the frabication or performs for optical fiver production. In this process, the particles convected with the carrier gas are deposited on the inner wall of the pipe due to thermophoretic forces. The deposition efficiency is obtained by numerically solving the differential equations governing conservation of mass, momentum, energy, and chemical species (particle concentration). The latter equation was solved utilizing a velocity field calculated by adding the carrier gas velocity to the thermophoretic velocity, obtained from the local temperature gradients. In order to assess the effects of axial thermophoretic velocities on particle deposition, the governing equations were considered in their elliptic form. The results presented revealed that the inlet which produce significant axial thermophoretic velocities and markedly influence the particle deposition efficiency.