ABSTRACT. Raia V. de A., de Carvalho Filho P.R., Pedrenho A.R., Flausino W. & Famadas K.M. Quantitative and qualitative evaluation of the egg proteins of Rhipicephalus microplus and Rhipicephalus sanguineus (Acari: Ixodidae) during oviposition. [Avaliação quantitativa e qualitativa das proteínas dos ovos de Rhipicephalus microplus e Rhipicephalus sanguineus (Acari: Ixodidae) durante a postura]. Revista Brasileira de Medicina Veterinária, 34(3):177-182, 2012. Departamento de Epidemiologia e Saúde Pública, Instituto de Veterinária, Universidade Federal Rural do Rio de Janeiro, BR 465 km 7, Seropédica, RJ 23890-000, Brasil. E-mail: e-mail: email@example.com To fill in some gaps in the knowledge of the intrinsic mechanisms of the oviposition biology of Riphicephalus microplus and R. sanguineus, the protein variability in eggs according oviposition day was evaluated. Engorged females laid eggs in a controlled environment chamber (27 ± 1° C, 80 ± 5% RH, and darkness). As soon as the females began oviposition, egg samples weighing 50 mg were collected daily, placed in Eppendorf tubes and preserved at - 20ºC. The protein concentration was evaluated by the Bradford method and submitted to analyses by SDS-PAGE. After normality of the data was excluded by the Shapiro-Wilk test, the data were transformed into logarithmic values [log (X+1)] and the protein concentrations were correlated with the oviposition days using Pearson’s correlation coefficient (r). During oviposition the egg protein concentrations of R. microplus and the days of lying were weakly positive correlated, while for R. sanguineus the egg protein concentrations remained constant until the last day. It cannot be inferred that the protein variation in the eggs of R. microplus is correlated with the oviposition day. The two tick species thus have different oviposition protein profiles, which can be use as a phenetic tool.