Intentional carbon doping of low‐pressure metalorganic chemical vapor deposition (MOCVD) grown InP has been attempted with a 500 ppm mixture of13CCl4in high‐purity H2, which has been used to obtain carbon‐acceptor concentrations as high as 1×1019cm−3in GaAs. Under growth conditions similar to those used for heavy carbon incorporation in GaAs, injection of13CCl4into the growth reactor during growth of InP did not produce any measurable change in the carrier concentration of the InP epitaxial layers or any change in the13C concentration above the13C background in secondary‐ion mass spectroscopy analysis. These results support previous low‐temperature photoluminescence measurements of high‐purity InP in which no residual carbon acceptor is observed under many growth techniques and growth conditions, and hence support the hypothesis that carbon is not incorporated in InP grown by MOCVD.