Effects of early-season damage by the citrus rust mite, Phyllocoptruta oleivora (Ashmead), on ‘Hamlin’ orange fruit growth and drop were studied from 8 June through 17 December 1991, in Hendry County, FL. ‘Hamlin’ fruit drop increased with increasing fruit surface damage by the citrus rust mite. The data also indicated a slightly accelerated fruit drop with increasing mite damage and time. The overall data suggested a slight negative relationship between fruit size and mite damage. Cumulative percentage drop and percentage diameter increase were fitted to two-variable logistic functions of damage and time. These functions could be used in management models for calculating volume losses from rust mite damage.