Corticosterone (CORT) is well known for its involvement in energy use and stress responses. Corticosterone peaks during frog mating, along with androgens. The relationships between endogenous CORT, androgens, body characteristics and male and female behaviors are still poorly understood. We studied these relationships in the gray tree frog, Hyla versicolor. Corticosterone dropped over the night of calling in males, while androgen was stable. Call properties were not correlated with hormone levels. Males with larger gonads were heavier with shorter intercall intervals. Longer males had longer intercall intervals. Amplexing males were longer and had heavier gonads. In female phonotaxis experiments, females with higher CORT levels were slower to reach the speaker. Thus, some body characteristics of males are associated with mating success or call properties. Our results in male treefrogs do not support the hypothesis that high CORT impairs mate success. In females, CORT may impair mate success.