A cytogenetic study of 27 spontaneous abortions was carried out using the Q-banding technic. The specimens were selected for study in order to increase the likelihood of finding a chromosome anomaly. Sixteen of 27 specimens (59%) showed a chromosome abnormality. Trisomy was found in 9 of the specimens, and the chromosomes involved were Nos 2, 8, 14, 16, and 22. There were 5 triploids and 2 tetraploids. Using marker chromosomes, it was found that the extra haploid set was paternally derived in two of the triploids which were favorable for study. The Q-banding technic provides accurate identification of the extra chromosomes in trisomy. When favorable markers are present in the parents, the source of the extra haploid set can be identified in triploid abortuses.