Wild Helianthus annuus naturalized in Argentina could be a valuable germplasm source for cultivated sunflower. Five wild populations collected in different environments and with different phenotype expression were evaluated as a genetic resource in a common garden study. The populations showed nor mal meiosis and produced a good seed set when their plants pollinated the male-sterile inbred line A09 (cms PET1). The wild populations restored more than 80% fertility of the HA89 (cms PET1) and A10 (cms PET1) inbred lines in the F1 generation. The fertility of one male sterile source from Mendoza was restored (>95%) by the maintainer line B10. The fatty acid composition differ entiated a population from Entre Ríos with a high saturated fatty acid content (>107 g kg-1). Another population from La Pampa showed a high level (>50%) of resistance to the Sunflower Chlorotic Mottle Virus (SuCMoV). No wild popu lations showed tolerance to imazaphyr sprayed at 2× doses (×=80 g i.a. ha-1). A population collected in the coolest environment showed high tolerance to low temperature (15/5°C, neutral day) in the initial grow stages (80%) under water stress (-0.4 MPa) imposed by polyethylene glycol 6000. This population and a second one from southern Buenos Aires showed the lowest leaf temperature increase (<10%) and the highest foliar specific den sity under artificial drought during the R4 to R6 reproductive stages. It was concluded that wild H. annuus naturalized in central Argentina can supply some useful traits for sunflower breeding.