Laser ablation of a BiSrCaCuO target is performed both in vacuum and in an oxygen pressure of 0.1 mbar. Two substrates are located in the chamber in order to study the role of re‐emission processes from the growing film and/or the scattering of the ablated species by an oxygen atmosphere. The results indicate that re‐emission processes from the growing film are very weak (they may affect up to 1% of the deposited material at most) and are not related to the re‐sputtering of the growing film. Films grown in vacuum are found to have the correct cation composition, whereas those grown in an oxygen environment show significant variations which are clearly related to gas scattering processes. ©1995 American Institute of Physics.