Hurricane Janice first appeared as a disturbed area south of Cuba. The first seven missions flown into the storm occurred on October 5, before it had attained hurricane intensity, the last on October 9, just before the storm experienced a rapid acceleration and intensification. The structure of Hurricane Janice during the developing and mature stages is described in this report. Profiles, horizontal cross sections, and radar photograph composites are presented. Particular attention has been given to the radar structure because of the somewhat three-dimensional nature of the data.