The symptomatology of Andean potato latent virus (APLV) was studied in several wild potato species and potato cultivars using isolates Caj, Hu and Ay from Peru. In greenhouse tests, the virus was latent in most isolate/cultivar combinations with primary infection but secondary infection commonly caused symptoms. Wild species infected with the different isolates normally reacted with symptoms with either type of infection. The main symptoms were mosaics, chlorotic netting of minor leaf veins and, with wild species, leaf deformation; the netting symptom was typical only with Caj. In infected cultivars growing in the field, an additional symptom, rugosity, sometimes also developed and environmental conditions at high altitude seemed to enhance symptom formation. Very severe symptoms were found in a cultivar jointly infected with APLV and Andean potato mottle virus. Transmission of APLV from an infected plant to its tubers was erratic.