I believe that animal testing for medical purposes is ethical. This is partially based on the utilitarian argument in ethics. Utilitarianism states that the most ethical choice is one that will produce the greatest good for the greatest number. Yet this is limited because you may test a drug on an animal and the outcome is that your drug doesn’t work. So you harmed an animal for no ultimate purpose. However the results can’t be predicted, thus animal testing is done in the hopes that greater good will be the result of your drug. Of course, special care must be given to the animal and it must be treated well. Also, when possible it is best to use the least complex animals for testing (such as the c.elegans worm).