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 dollar 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.