Abstract: In 2001, 1.458 million American families filed for bankruptcy. To investigate medical contributors to bankruptcy we surveyed 1771 personal bankruptcy filers in five Federal courts, and subsequently completed in-depth interviews with 931 of them. About half of debtors cited medical causes, indicating that between 1.850 and 2.227 million Americans (filers plus dependents) experienced medical bankruptcy. Among individuals whose illness led to bankruptcy, out-of-pocket costs averaged $11,854 since the start of illness; 75.7% had insurance at the onset of illness. Medical debtors were 42% more likely than other debtors to experience lapses in coverage. Even middle class, insured families often fall prey to financial catastrophe when sick.