Free medication samples, which at first glance look like a win-win-win situation for manufacturers, doctors, and patients, can have hidden costs. Doctors might pick a sub-optimal drug simply because they have a sample. Plus, only makers of expensive brand-name drugs are doling out samples, and leaving pharmacists out of the equation might raise the risk of errors. Recognizing that, health systems around the country are beginning to curtail the practice, a major marketing tool. In January, a study in the journal PLoS Medicine estimated that in 2004, drugmakers handed out free samples to U.S. doctors with a retail value of nearly $16 billion, equal to more than a quarter of their marketing budgets that year.