Aspects of the reproductive biology of male and female Agkistrodon piscivorus are described using histological techniques, reviewed, and compared with historical data on A. piscivorus. These include anatomical description at the macro and microscopic levels, and correlation of the male and female urogenital cycles to the reproductive life history of A. piscivorus. New anatomical descriptions and discussion of the efferent ducts, including the ductuli efferentes, proximal and distal ductuli epididymides, ductus deferens, and ampulla ductus deferens, are also presented here at the light and electron microscopy levels. Morphology of all distinct regions of the male and female urogenital systems are discussed and compared with historical investigations on other squamates. In comparison to other snakes, A. piscivorus possesses some unique reproductive characters, whereas others are more conserved. In terms of the reproductive cycle, the ability of males and females to store sperm allows the dissociation of reproductive event timing between the sexes. Thus, the only event that must be coordinated between the sexes is copulation, which is proposed to occur in the fall and the spring in A. piscivorus. In females, the atrophy and activity of the reproductive organs (e.g., secretory activity) varies concurrently with vitellogenesis and the mating seasons. In males, spermatogenesis peaks in the summer, independent of the mating season, except in Louisiana where a spring and fall peak of spermatogenesis occur, and where the spring and fall mating seasons overlap. Renal sexual segment hypertrophy in males peaks in the fall and spring in more southern populations (Alabama and Louisiana) concurrent with fall and spring mating seasons. In Georgia, only a fall peak is observed. Secretory activity of the male excurrent ducts also peaks during times of mating activity in one population studied (Louisiana).