Analyses are made on the birth weights of 422 patients with autosomal trisomy and partial deletion. It is found that in the autosomal trisomy groups, the mean birth weight of newborn controls is significantly heavier than that of those with Down’s syndrome, trisomy D13 and trisomy E18. In these three autosomal trisomies, the order of birth weight in decreasing fashion is trisomy 21, trisomy D13 and trisomy E18. For the group of patients with partial deletion of the autosomes, the mean birth weight of newborn controls is heavier than that of those with deletion B4p, deletion B5p, ring D and ring A1. Among all the patients with different ring chromosome anomalies, those with ring D and ring A1 have the lowest mean birth weights.