-Mite infestations to the culture of mate-tea frequently causes losses by the premature fall of the leaves. So, it is necessary to monitor the population of these arthropods, and to adopt management strategies for their control. The objective of this research was to evaluate the trustworthiness of presenceabsence sampling for Oligonychus yothersi (McGregor) on mate-tea orchard. This study was conducted in Cascavel, Paraná State, from April 2001 to July 2000, in a mate-tea tree commercial plantation. Biweekly sampling of 240 leaves were collected in different parts of 10 plants, and the number of mites was counted. The aggregation pattern was determined through the coefficients a and b of Taylor's power law. The proportion of infested leaves and the number of required samples were estimated through mathematical model. The mite O. yothersi presented aggregate distribution. The proportion of infested leaves calculated by means of mathematical model showed to be a trustworthy parameter to estimate the population density of the mite. The number of required samples was small, making feasible the practical application of the presence-absence sampling method for O. yothersi in the culture of mate-tea. Com a devastação das matas de araucária, as áreas de exploração da erva-mate se reduziram e conseqüente diminuiu a oferta de matéria-prima para a indústria ervateira. Frente à necessidade de atender à crescente demanda do mercado, foi estimulado o plantio de ervais em monocultivo. A formação de povoamentos puros, além de provocar alterações fisiomorfológicas nas plantas, interferiu na complexa cadeia alimentar, acarretando rápido aumento populacional de muitas espécies fitófagas (Penteado 1995, Gouvea et al. 2006. Esse foi o caso dos ácaros, resultando em perdas na produção, pela queda precoce de folhas e secamento de brotações (Alves et al. 2004). Entre os ácaros está Oligonychus yothersi (McGregor), praga também conhecida por ácaro-roxo ou ácaro-vermelho da erva-mate.Aumentos na densidade populacional e nos danos causados por esse ácaro, em determinados períodos e