Analogue functional analysis methodology was used to assess potential maintaining contingencies of episodic self-injurious behavior (SIB) of a 4-year-old child diagnosed with autism. Analogue conditions were presented within a multielement design when the child did, and did not exhibit signs of a possible sinus infection, and when the participant, did, or did not, wear a weighted vest. Findings revealed higher occurrences of SIB when a sinus infection was considered to be present vs. absent, and the weighted vest did not affect occurrences of SIB during the functional analysis. SIB was considered to be maintained by some form of automatic reinforcement. Implications for enhancing functional analysis methodology by including measures of biological events such as medical illness are discussed. (Contains 1 figure.)