Benthic macroinvertebrates and physicochemical parameters were monitored simnl taenously with hydrilla (Hydrilla verticillataRoyle) biomass in a Central Florida lake. Twenty-seven of the 54 taxa of benthic macroinvertebrates collected were members of the family Quronomidae. Chironomids and oligochaetes numerically dominated the benthos, comprising 82% of the individuals collected. The greatest numbers of taxa and individuals were found during the winter when hydrilla biomass was low. Hydrilla biomass ranged from 0.382 kg/m2-FW in April, 1977 to 2.275 kg/m2-FW in October, 1977. Low numbers of macroinvertebrate taxa and individuals were collected from bottom sediments during sunnier and fall. Dissolved oxygen concentrations at the bottom were approximately 2.0 ppm during summer and fall and possibly limited benthic organisms. The annual means for the Shannon and Simpson indices for the benthos were 1.92 and 0.35, respectively.