Doucet, M. E., P. Lax, E. Lorenzo, C. Gallardo, and S. M. de L'Argentier. 2007. Histological observations of sedentary plant-parasitic nematodes in two varieties of Andean potato (Solanum tuberosum L. subsp. andigenum) from northern Argentina. Nematropica 37:121-125. Histological alterations on roots and stolons of Andean potato (Solanum tuberosum subsp. andigenum), Colorada variety induced by Nacobbus aberrans, Globodera pallida and Meloidogyne sp. are described. The host was found to be susceptible to these three nematodes. A similar response to the parasitism of N. aberrans was observed in roots of Ojosa variety. Results show that these nematodes cause serious damages in these two Andean potato varieties from the North of Argentina.