Collection records of Culex pipiens sensu strictu from the Patagonian region of Argentina are presented. These records confirm the occurrence of this species in Rio Negro Province, and establish its presence in Chubut Province. Laboratory studies showed a high rate (77%) of autogeny among progeny of field-collected females from near Trelew, Chubut Province. This biotype also bites humans under insectary conditions. A general outline of the distribution of the Cx. pipiens complex in Argentina is given. Culex quinquefasciatus occurs from Buenos Aires and Mendoza Provinces northward, and Cx. pipiens form Buenos Aires southward through Santa Cruz Province.