The physical and dermatoglyphic features obtained from published reports of 128 patients with the trisomy 9p syndrome and 27 patients with the partial 9p monosomy syndrome are tabulated. This information is also provided on two new individuals with each of these chromosomal disorders. The dermal ridge patterns and palmar creases of trisomy 9p which are most helpful from a diagnostic standpoint are zygodactylous or absent palmar digital triradii, brachymesophalangy, reduced total finger ridge count, complex thenar/ID I patterns, transverse palmar ridge alignment, simian creases, distal axial triradii, and great toe and hallucal arch patterns. The characteristic features in partial 9p monosomy include dolichomesophalangy with accessory finger flexion creases, digital whorl patterns and elevated total finger ridge count, distal axial triradii, simian creases, and palmar dermal ridge dissociation.