Currently, there are 122 hemophiliacs in Madagascar followed at the hemophiliac treatment center of the Joseph Ravoahangy Andrianavalona University Hospital Center (JRA UHC), 55 present hemophilia B and 67 of hemophilia A. In hemophilic patients, the diagnosis of hemarthrosis is obviousin front of articular inflammation. It's important to determinate the main risk factor as well as predisposition indicators tothe occurrence of "spontaneous" hemarthrosis in hemophiliacsfor prevention andearly careanticipation. In this prospect, the search for potentpredisposition indicator such as immunologicalfactorsis important. This is a case control study on all hemophiliacs seen at (JRA UHC) with hemarthrosis for 7 months. We have descriptively studied the qualitative and quantitative variables consisting in the determination of rheumatoid factors (RF) and the titer of antistreptolysin O (ASLO). Then we studied the statistical correlations. During the study period, we included 30 hemophiliac subjects with hemarthrosis who had an average age of 16.8 years. We had as much hemophiliac A as hemophiliac B; 23.3% practiced sporting activity; 10% had history of angina, involvement of the knee joint predominated at 44% (left 24%). RF positive were present in 26.7% (8/30) predominant in hemophiliacs aged from 19 to 36 (62.5%). The ASLO positive titer was found in 43.3% (13/30) predominant in children from 5 to 13 years (38.5%) with a maximum rate of 1600IU / l. There was no significant relationship between the positivity of the parameters with the presence or absence of hemarthrosis with a value of p = 0.231 and p = 0.06 respectively (p > 0.05). A large number of hemophiliac patients had a combination of clinical and biological signs in relation to diagnose rheumatic fever and rheumatoid arthritis which must be monitored as this could predict the occurrence in the short and medium term of these diseases which could be mistaken for hemarthrosisrelated to hemophilia.