This paper presents an acid-base interpretation drill written for the Sharp PC-1211 and the Radio Shack TRS-80 PC-1 computers. The computer generates random numbers for Pco2 and HCO3 - and calculates pH, then interprets the values according to a normal values key and a 13-item interpretation key. Next, the computer asks for the user's interpretation of the values, evaluates the user's interpretation, and informs him whether his answer is correct or incorrect. If it is incorrect, the user has the option of trying again or directing the computer to display the correct answer. The user is then given a chance to interpret a new set of acid-base values. I have found that this method of instruction enhances students' enthusiasm for learning and relieves the instructor of the tedious aspects of teaching acid-base interpretation. (Hess D. The Hand-Held Computer As a Teaching Tool for AcidBase Interpretation. Respir Care 1984;29:375-379.