A REVIEW of a large series of cases of verified bone and joint tuberculosis has impressed us with the unusual and varied roentgen findings. In many instances the roentgenographic appearance of the lesion has been so at variance with the criteria commonly accepted as evidence of bone and joint tuberculosis that it is our opinion that a roentgen diagnosis is not only difficult but in many instances inconclusive. A knowledge of the clinical course and general condition of the patient is indispensable in arriving at an accurate interpretation, and frequently histologic studies are the only means of reaching a positive diagnosis. Two hundred cases of bone and joint tuberculosis were chosen at random from the vast amount of material available at Sea View Hospital. The tuberculous nature of the disease process was verified in each instance. The cases were equally distributed between the pediatric and adult services of the institution, there being one hundred in each group. Patients under the age of sixteen were included in the former group, those sixteen and over in the latter. Statistical Study Age Incidence.—In the age group one to sixteen there appears to be a natural division into two subgroups, between the years nine and ten (Table I). Of the 100 cases, 70 were in the one to ten year subgroup and 30 in the ten to sixteen year subgroup. This predominance in the early age group is true of both sexes. Seventy-five per cent of the cases in males and 65 per cent of those in females occurred during these years. In the female sex there is again a definite rise in incidence at fifteen years. This may be attributed to the effects of puberty. Whether this predominance in younger children is to be attributed to the initiation of active bone disease during an early post-primary hematogenous dissemination, or to the reactivation of a focus previously deposited, is a debatable question. In view of the fact that 28 patients presented definite roentgen evidence of a fresh or resolving primary pulmonary lesion (Table V) it is probable that the osseous involvement was initiated during and progressed from the time of early post-primary dissemination. In the adult group of cases, the ages ranged from sixteen to seventy years. As is apparent from the accompanying table (Table I), the frequency with which bone tuberculosis occurs in the various adult subgroups corresponds to those ages at which physical activity is most strenuous and pulmonary tuberculosis most prevalent. From sixteen to twenty the number of cases approximates that in the pediatric group. Immediately thereafter, twenty to twenty-five, there is an abrupt rise to the maximum incidence, followed by a gradual decline till the subgroup forty to forty-five is reached. At this point, which marks the division between the adult and old age subgroups, there is a sudden and distinct drop in incidence.