A number of crosses were made between Papaver rhoeas and P. dubium. Only a few data are available but they may be considered as an addition to the data given by Rogers (1969). Out of 246 attempted P. rhoeas X P. dubium crosses 36 were successful, whereas out of 57 attempted reciprocal crosses 18 succeeded. The germination of the hybrid seed was somewhat better, whereas seedling mortality on the whole was lower than mentioned by Rogers.