Ticks collected from dogs which were brought to the Veterinary Teaching Hospital of Tuskegee University were used for various experiments on the biology of the egg-phase. These included oviposition patterns, relationships between engorgement weight, number of eggs laid and rate of metabolism of oviposition tick, the sizes of eggs and their embryonic development, fluctuation of weight of egg-batches during embryonic development and the fluctuation of the weight of single freshly laid eggs within the sequence of oviposition. The Maximum Effective Engorgement Weight (MEEW) was defined to characterize the weight - specific for each species - at which the number eggs laid is not influenced by the engorgement weight. Individual capability of engorged ticks to lay large or small numbers of eggs after attainment of MEEW was observed and this led to the recognition of two oviposition capabilities within a given tick species i.e. high and low. Amblyomma maculatum had the biggest eggs followed by Dermacentor variabilis and then Rhipicephalus sanguineus. Eggs of the species hatched as long as they were ’egg-shaped’ and not circular. In addition, eggs of R. sanguineus which were less than 0.30 mm failed to hatch irrespective of their shape. The viability of eggs laid by R. sanguineus and D. variabilis which engorged on dogs was higher than that of eggs laid by females which engorged on rabbits. The phases of embryonic development of eggs were described as well as the microscopic structure of the egg-shells.