Purpose: To evaluate the risk factors for the development of osteonecrosis in civilian professional divers by an epidemiologic study and to determine the correlation between osteonecrosis in divers and coagulopathy by analysis of serologic markers that are related to thrombophilia and hypofibrinolysis. Materials and Methods: Forty-two divers, who collected pen shells (Atrina pinnata), and among whom 10 had osteonecrosis (group 1), were compared with 32 divers without osteonecrosis (group 2). Both groups were evaluated based on the number of years of diving experience, number of dives per year, mean number of dives per day, mean diving time and depth, and diving methods. We determined any statistically significant differences among these variables. We measured the levels of serologic markers that were related to hyperlipidemia, thrombophilia, and hypofibrinolysis from the divers and a control group of 20 physicians (group 3). The levels of the serologic markers were compared between groups 1 and 2 and between the divers and the control group, in order to determine the relationship between the serologic markers and the development of dysbaric osteonecrosis. Results: None of the variables demonstrated any statistically significant differences, except for the mean diving time, in which group 1 had a mean diving time of 124 minutes and group 2 had a mean diving time of 62.1 minutes (P<0.05). In the analysis of the serologic markers, there were no statistically significant differences between groups 1 and 2; however, in comparison with the group 3, the divers demonstrated significantly decreased activity levels of proteins C and S (Protein C: P<0.05; Protein S: P<0.05), and an increase in the levels of plasminogen activator inhibitor-1 (PAI-1) (P<0.05). Conclusion: The divers with osteonecrosis had a longer mean diving time than did those divers without osteonecrosis. In the serologic marker analysis, the divers with osteonecrosis demonstrated significantly decreased activity levels of Proteins C, S and a significant increase in the levels of PAI-1, compared with the control group.