Association between traits for hormonal status and nodulation in the mutants of pea Pisum sativum L. with abnormal nodulation and original forms was analyzed. The sensitivity of plant tissues to exogenous phytohormones and changes in the concentration of the major auxin, indolyl-3-acetic acid, in plant roots during interaction with rhizobia were examined. Association between Nod⁺⁺-phenotype and auxin balance was revealed: the supernodulating mutants were more sensitive to auxin treatment than the parental cultivars. Mutations in the sym8 gene, in contrast to those in the sym5 gene, had no effect on plant hormonal status. The level of indolyl-3-acetic acid during interaction with rhizobia depended on the time after inoculation and plant genotype. The mutations affecting nodulation were suggested to change auxin level in roots.