SI units for clinical laboratory data.

The international System of Units (SI) has not yet been accepted by American physicians because of reluctance to convert to a new system and the corresponding need for relearning. The impetus to introduce the SI came from European laboratory scientists; the system was later accepted (not always enthusiastically) by physicians after the same objections now voiced by their US counterparts were overcome. Now that many American laboratory scientists are actively studying and assessing the benefits of SI, we may have begun the chain of events that will lead to general acceptance by physicians in the United States.