The purpose of this study was to determine whether an in-service for public health nurses (PHNs) and accompanying educational materials could improve vaccine risk/benefit communication. The content and timing of vaccine communication were recorded during 246 pre-and 217 post-intervention visits in two public health immunization clinics. Pre-/postintervention comparisons showed PHN communication of severe side effects (13% vs. 44%, p less than 0.0001) and their management (29% vs. 60%, p less than 0.0001) increased. There was no significant change in discussion of vaccine benefits (48% vs. 51%) or common side effects (91% vs. 92%),screening for contraindications (71% vs. 77%), or distribution of written information (89% vs. 92%). More parents initiated vaccine questions postintervention (27% vs. 39%,p less than 0.01) and were more satisfied with vaccine-risk communication (8.1 vs. 8.9 on a 10-point scale, p less than 0.01). Average vaccine communication time increased from 16 to 22 seconds (p less than 0.01). (Contains 3 tables and 1 note.)