A field trial was conducted on five farms to determine the effect of feeding distillery dried grains (DDGS) on milk production in the southern dairy region of Chile. The trial was repeated on each farm during winter (July and August; primarily silage-based rations) and spring (November and December; pasture-based rations). Only for one farm could the treatments be applied concurrently by feeding different iso-nitrogenous concentrate mixes to randomly assigned cows in the milking parlor with data analyzed as a randomized complete block design. Milk yield tended (P < 0.07) to be greater for cows fed DDGS (2.0 kg cow-1 d-1) by 1.9 kg d-1 in winter and 1.8 kg d-1 in spring. In winter, milk protein yield was (P < 0.02) greater for cows fed DDGS by 73 g d-1. Milk fat content was (P < 0.01) lower for cows fed DDGS by 0.26%-units in the spring, however, milk fat yield was unaffected by treatment. The four farms that could not apply the treatments concurrently were randomly assigned to either a control to DDGS or a DDGS to control iso-nitrogenous concentrate treatment sequence in a Crossover design with monthly feeding periods during the winter and spring. Data were analyzed as a Crossover design with farm as the experimental unit. Milk yield was (P < 0.05) greater for farms fed DDGS (2.5 kg cow-1 d-1) by 0.9 kg d-1 in winter. We conclude that DDGS was an effective dairy concentrate ingredient in the southern dairy region of Chile.