To assess and correlate the microbiology of neonatal septic arthritis with the clinical presentation, we reviewed the records of nine infants with neonatal septic arthritis (NSA) diagnosed at Edmonton hospitals between 1964 and 1981, and evaluated 92 other cases reported in the English literature since 1960. Our analysis revealed that the microbiology of NSA seemed to be dependent on whether it was hospital or community acquired. In the hospital-acquired cases, staphylococci were the predominant isolates (62%), followed by Candida species (17%) and gram-negative enteric bacilli (15%). Community-acquired arthritis was caused most often by streptococci (52%), followed by staphylococci (26%) and gonococci (17%). Since 1970, the relative infrequency of staphylococcal (5%) in favor of streptococcal (75%) isolates in community-acquired NSA is even more pronounced.