Chinese hamster cell mutants resistant to the lectins PHA, WGA, RIC, LCA, and CON A were previously grouped into 8--10 distinct phenotypes on the basis of their unique patterns of lectin resistance and lectin-binding properties. All but one of these classes of lectin-resistant (LecR) mutants behave recessively in somatic cell hybrids. One ricin-resistant class (RicRII) behaves dominantly. Tests for complementation, by measuring the lectin-resistant properties of appropriate hybrids, show that seven distinct complimentation groups can be delineated among the phenotypically recessive mutants.