Hibiscus rosa-sinensis L. plants treated three times with 850 mg·liter-1 of the growth retardant chlormequat chloride (CCC) were less susceptible to infestation with Tetranychus urticae (Koch) than water-treated control plants. The difference in mite numbers was noted within 8 days after releasing mites onto test plants. Mean number of mites per treated plant was 3.7, compared to 30 on nontreated plants. This activity was observed on all treated plants 6 months after applying CCC. Significant differences were observed on treated plants that were defoliated and allowed to produce new foliage before being evaluated. Therefore, surface chemical residues were not responsible for reducing mite infestations on CCC-treated plants.