In 2001, 1.458 million American families filed for bankruptcy. To investigate medical contributors to bankruptcy, we surveyed 1,771 personal bankruptcy filers in five federal courts and subsequently completed in-depth interviews with 931 of them. About half cited medical causes, which indicates that 1.9–2.2 million Americans (filers plus dependents) experienced medical bankruptcy. Among those whose illnesses led to bankruptcy, out-of-pocket costs averaged $11,854 since the start of illness; 75.7 percent had insurance at the onset of illness. Medical debtors were 42 percent more likely than other debtors to experience lapses in coverage. Even middle-class insured families often fall prey to financial catastrophe when sick.