Complete medical evaluations were performed on 25 wild black lemurs (Eulemur macaco macaco) in Lokobe Reserve, northwestern Madagascar. Each animal received a complete physical examination. Weight, body temperature, heart rate, and respiratory rate were recorded. Blood samples were collected for complete blood cell count, differential white blood cell count, hemoparasite examination, serum biochemical profile, fat-soluble vitamin analysis, trace mineral analysis, and Toxoplasma gondii and viral serology. Fecal samples were collected for bacterial culture and endoparasite examination. Ectoparasites were collected and identified. Values were compared to established ranges from captive black lemurs in North American zoos. Significant differences exist between captive and wild animals for total white blood cell count, segmented neutrophil count, band neutrophil count, eosinophil count, monocyte count, and basophil count, and for serum biochemistry values of aspartate aminotransferase, alanine aminotransferase, total bilirubin, serum alkaline phosphatase, total protein, creatinine, phosphorus, calcium, sodium, potassium, and creatine phosphokinase. One animal had a positive Toxoplasma titer. Detected endoparasites were identified as Lemuricola and Callistroura. Two ectoparasite mites were identified, one within the Psoroptes genus and one within the Laelapidae family. Enteric bacterial flora included Enterococcus sp., Staphylococcus sp., Escherichia coli, Streptococcus sp., Klebsiella ozaenae and Bacillus cereus.