Eucapnic voluntary hyperpnea (EVH) challenge is a well-established and sensitive method of determining the degree of bronchoconstriction at hospitals and clinics. This paper presents the development of a computer-controlled system for assessing exercise-induced bronchoconstriction (EIB) in humans including a computer graphic user interface (GUI) to control a low-pressure demand valve for better efficiency. GUI is designed to monitor the severity of acute lung airway narrowing using a matlab software and to present the measurement data into a simple user-friendly program consisting of patient information, EVH test analysis, and detection of exercise-induced asthma (EIA) and EIB. The proposed system is assessed using human subjects. Typical outputs from this system showed that for a female participant, a 20.25% and a 15.61% decrease from baseline in her forced expiratory volume in 1 s (FEVl) after 10 and 15 min of the challenge commencement, respectively. Her actual expiratory flow rate (45.833 L/m) and actual total volume of gas respired (275 L) were smaller than the target values. This system widens the usage of EVH challenge in medical areas, and the GUI may serve as a new clinical computer-aided diagnostic tool to help healthcare professionals noninvasively monitor the severity of asthma, EIA, and EIB.