Fifty-seven 4-10-year-old pediatric medical clinic patients and their mothers were observed while awaiting a diagnostic examination. The Dyadic Prestressor Interaction Scale (DPIS) was used to assess mother and child behaviors. Child distress during the examination was measured by the Observational Scale of Behavioral Distress (OSBD). Lag sequential analysis indicated that when mothers who self-reported high state anxiety (STAI) exhibited agitation, child distress (DPIS) increased (p <. 05). The reverse sequence, an increase in maternal agitation following child distress (DPIS), occurred among low anxious mothers (p <. 005). Additionally, irrespective of state anxiety, mothers who became agitated following DPIS child distress, had children who during the exam showed high OSBD distress (p <. 01). Results indicate the importance of mother-child interactions as a factor in children’s medical stress. © 1988 by The Haworth Press, Inc. All rights reserved.