In recent years, grunting has become a familiar although generally unwelcome element of tennis. The behavior is considered to deny opponents the benefit of receiving optimal multi-sensory information in order to plan their own shots. The ability to make accurate serve-speed judgments of identical tennis serves presented on a computer screen, and accompanied by a grunt or not, was assessed among 38 participants (19 men). Accuracy and response time were measured. Analysis compared performance for below versus above average speed serves and for the grunt versus the no grunt condition. Grunting had a disruptive effect on serve-speed perception for below average serves, with most judged incorrectly to be above average. Response times for below average serves were also slower in the grunt condition. Grunting provides a complex perceptual challenge, and greater effort may be attributed to tennis serves with an accompanying grunt.