Microspore-derived plants were produced via anther culture in Brassica campestris. The cytological analysis of these plants revealed the existence of diploids, tetraploids as well as haploids. In these plants, the number of chloroplasts in guard cells were clearly related to the ploidy level. The number of chloroplasts in mesophyll protoplasts was also related to the ploidy level, though the relationship was not as clear as in guard cells. The number of chloroplasts in both types of cells increased after the number of chromosomes was artificially doubled with colchicine.