The skeletal remains of an infant from a southwest South African rock shelter at Byneskranskop show pervasive abnormalities that are consistent with the effects of hypertrophic (hyperplastic) rickets. Diagnostic features include beading of the costochondral junctions of the ribs, flaring and tilting of the metaphyses, and cupping of the distal ulna, as well as general skeletal hypertrophy. With an uncalibrated accelerator mass spectrometry (AMS) radiocarbon date of 4820 ± 90 BP (TO-9531), this is a very early instance of the condition, among foragers whose environment and diet make dietary shortages of active vitamin D or dietary calcium improbable. Carbon and nitrogen stable isotope ratios indicate a mixed diet, including marine as well as terrestrial protein. Solicitous care maintained the sick infant to an estimated age of 3.5–5 months; it was buried in a manner like that of other deceased group members. This case suggests that if infanticide was practiced, it was an option only during the immediate perinatal period, when this infant would have appeared normal. This is consistent with documentation of infanticide practices among historic foragers from southern Africa. Am J Phys Anthropol, 2003. © 2003 Wiley-Liss, Inc.