Planetary nebulae (PNe) around [WR] central stars (WRPNe) constitute a particular photoionized nebula class, representing about 10-15% of the PNe with known progenitor. We have studied 14 of them, detecting a large number of optical recombination lines (ORLs) from different ions of O and C (O+, O++, C++, C+3). This allows us to determine the C/O ratio, which is of paramount importance to constraint stellar evolution models. We have compared the obtained N/O and C/O ratios obtained with those derived from stellar evolution models, and we estimate that about half of our PNe have progenitors with initial masses similar to or larger than 4 Msun . These results are consistent with the results obtained from an independent analysis by Górny & García-Hernández (2014).