The resistivity of the Bi‐Sr‐Ca‐Cu‐O thin films deposited by MOCVD (metalorganic chemical vapor deposition) has been investigated. Samples of thickness from 5 to 300 nm have been studied. Zero resistance temperatures (Tc0) for all samples were about 70 K. For all samples,Tc0was nearly independent of magnetic fields up to 6 Tesla applied parallel to the film surface. In contrast,Tc0decreased significantly in fields applied perpendicular to the film surface. We suspect this difference to originate in the nonpenetration of flux quanta (due to the large effective lower critical field for thin film in the parallel field case) and in the potential barrier to flux penetration at the surface of the thin films in addition to the natural anisotropy of the Bi‐based superconductors.