Anecdotal accounts by parents and medical professionals suggest children with ASD become more social, communicative, and engaged during episodes of fever. This study explored the “fever effect” using the AVACEN 100, a device designed to slightly warm the blood, to determine if children with ASD improved on measures of communication and functioning. Three tests were conducted: the Parents Stress Scale, the Childhood Autism Rating Scale-2nd edition reported by parents’ and objective coders’ ratings of videos, and the Pragmatics subtest of the Clinical Evaluation of Language Fundamentals-5th edition. There were two phases in the study, each lasting 6 weeks. Phase 1 was double-blind, with participants being categorized into active treatment, heat treatment without vacuum, and placebo control. Phase 2 was open-label and participants in former control groups received the active treatment. In both phases each set of tests was completed at the beginning, middle, and end of the 6-week period. There were 13 participants in Phase 1. Due to attrition, only 6 of the 13 participants continued to Phase 2. The mean age and range of participants was 11.6 years (4.5-17.1), and 10.7 years (8.5-14.8) in Phase 1and Phase 2 respectively. Qualitative anecdotal analysis was based on the parents’ perceived improvements in behavior, diet, language, and sleep. Some subjects in each of the three groups showed trends toward improvement, however quantitative statistical analysis showed no significance across any group or within any individual participant, demonstrating that AVACEN 100 was not a more effective treatment than placebo controls for the participants in this small pilot study.