Does the title of this article strike home with you as an important issue in the classrooms or laboratories in your school? Have you, your fellow teachers or your local school board discussed the accidental spread of AIDS (Acquired Immune Deficiency Syndrome) virus during a seemingly harmless laboratory exercise? Have you thought about the many ways that this virus, hepatitis or other viruses might be transmitted inadvertently in the classroom? We pose these questions NOT to frighten, but rather to stimulate thought and discussion about a potential but largely preventable problem. Before answering these questions, we would like to offer the following considerations. It is a generally accepted principle of microbiology that a disease can occur as the result of an infectious particle being transmitted from one host to another. The AIDS virus, like all viruses, is a transmissible particle. It is also thought to be spread via sexual contact or the use of needles shared by intravenous drug users, and to hold little possibility of being transferred by casual contact. However, it cannot be assumed that there is no transfer of blood between individuals during or after the typing exercise. Because of the possible dangers, we offer the following examples of how virus contaminated blood may inadvertently contact other students, faculty members and/or custodial or stockroom staff. Although it is statistically unlikely that one of your students is unknowingly carrying the AIDS or hepatitis virus, it does not mean there is no reason to consider their potential of spreading. These are some possible ways this can happen: 1. Blood lancets, even though you have a container for proper disposal, may be placed inadvertently in the wastebasket where they pose a threat to custodians. Other students may also come in contact with lancets before they are properly discarded. 2. Some students bleed more than the necessary one or two drops. Often the excess blood falls on the desk or laboratory bench where other students, teachers and custodial staff may come in contact with it. 3. Any excess blood is often wiped off the finger with cotton or a paper towel and thrown into a wastebasket. Again, anyone reaching into the wastebasket for any reason is at risk of contacting the contaminated items. 4. The slides used to do the actual blood typing present perhaps the greatest source of danger. How often have you seen these slides dropped and broken? Anyone who picks utp the broken pieces is in jeopardy of not only coming in contact with the blood, but also cutting themselves in the process. How much different is this from sharing a hypodermic needle? 5. The process of cleaning slides presents an obvious hazard to stockroom staff. Or, if students clean their slides, how well do they perform the task? Of course you may argue that touching contaminated blood does not allow the virus to enter the blood stream. Consider, however, that people often have scratches, particularly on their hands. Furthermore, they also rub their eyes, place their fingers in their mouths, etc. Again, we repeat that the likelihood of this kind of accident occurring is small. However, anything that is done to reduce the risk of even one case of AIDS is worthwhile. Whether you choose to discontinue blood typing exercises or to be much more cautious than in the past, we hope that you think seriously about the above. Also, you may wish to discuss the risks/ benefits of blood typing with school administrations and appropriate parent groups. Remember, even if students are required to have parental permission it will not protect those who are not participating in the exercise. Finally, on a positive note, you may elect to use altemative methods for demonstrating the principles involved. For example, you might use outdated and screened blood from a local hospital or blood bank. Computer simulations or demonstrations using an overhead projector are also possible alternatives.