Many termite colonies survive the loss of primary reproductives by producing replacement reproductives that differentiate from workers and nymphs and are termed ergatoid and nymphoid neotenics, respectively. Numerous male and female neotenics have been observed in termite colonies, but the numbers that are actually reproducing has not been investigated. Our study of Reticulitermes flavipes (Kollar) neotenics assessed their reproductive competency using histological techniques to determine if the vasa deferentia or spermatheca contained spermatozoa, which are aflagellate, spherical, and about 2 µm diameter. Three laboratory colonies have been examined to date; two colonies had almost equal numbers of female and male neotenics (37:35, 4:3) and one colony was significantly female skewed (10:2). Spermatozoa were detected in all male and female neotenics. Spermatheca size (diameter of the recurved tip) was not significantly different between ergatoid and nymphoid neotenics. However, ergatoid and nymphoid neotenics showed considerable variability in terminal oocyte size, which ranged from <200 µm to >800 µm diameter. No spermatozoa were observed in the spermatheca of immature termites, which served as controls for each colony. The testes and spermatheca of immatures were much smaller than that of neotenics. In a related project, female swarmers were found to lack spermatozoa in the spermatheca which confirms published literature that insemination of alates does not occur in the natal nest. A mucus-like substance in the lumen of their spermatheca was observed for the first time in termites; this may serve as a sperm energy source as has been documented in some other insects.