Macrophages in cerebrospinal fluid are described as indicators of pathology. We present findings from the lumbar puncture of a child without neurologic disease. Cerebrospinal fluid obtained after an initial, traumatic lumbar puncture attempt included a high proportion of macrophages, some containing erythrocyte fragments and hemosiderin. This suggests that although macrophages may indicate pathology, they can also accumulate after traumatic lumbar puncture.