The black rhinoceros, endangered in the wild due to illegal hunting for its horn, also faces threats to its survival in captivity. A skewing of the natal sex ratio favoring males is a problem of increasing concern for the captive black rhino population. A retrospective case-control study was conducted to examine risk factors associated with the birth of a male calf. The outcome variable was the birth of a male calf. A generalized linear mixed model was constructed using a backward selection strategy. A skewed natal sex ratio was found in calves born to wild-born dams. Increased time in captivity was associated with an increased likelihood of a male calf, whereas the age of the dam between 12 and 19 years had a decreased likelihood of a male calf. No associations were found with the birth of male calves to captive-born dams. A study including 296 of the 334 black rhinos (88.9%) ever in captivity in the United States in facilities accredited by the American Zoo and Aquarium Association (AZA) between the years 1930 and 2001 found that 35% of the animals have died without reproducing. This study also revealed that cases of primary hemolytic anemia peaked in the years 1976 -1980 and do not currently represent a major health problem to the captive population. This study identified cases of idiopathic hemorrhagic vasculopathy that occurred prior to 1995 and in animals living in regions other than Texas. Cholestatic hepatopathy, originally reported as toxic hepatopathy associated with creosote exposure, was found in cases with no documented exposure to creosote. Additionally, several cases were identified that had lesions of both cholestatic hepatopathy and idiopathic hemorrhagic vasculopathy. Survival analysis, using the Cox proportional hazards model, was performed to study the effects of disease parameters on survival. Several documented disease syndromes, idiopathic hemorrhagic vasculopathy and superficial necrolytic dermatopathy, were found to have adverse effects on survival. In addition, this study revealed previously undocumented health problems, including dental calculus and neurologic signs, that have negative impact on survival of the captive population. Housing animals in multiple institutions over time was associated with decreased survival.