Sixteen 1-year-old castrate Dorper sheep were used for the study. The animals were divided into four groups of four animals (n = 4). Three groups were implanted with 129 g, 258 g and 387 g of thin plastic bags into the rumen through rumenotomy, while the fourth group was subjected to rumenotomy without implanting plastic bags, and served as control. All the animals were monitored daily for 6 weeks following implantation. Presence of plastic bags in the rumen was characterized by anorexia, severe depression, discomfort, dehydration, firmness and asymmetrical distension of the abdomen, ruminal hypomotility and diarrhoea with intermittent constipation, weight loss, terminal recumbency and death. The severity of these clinical manifestations increased with increased quantities of plastic bags and their duration in the rumen. Sheep implanted with 258 g and 387 g lost 7.8 percent and 14.2 percent of their initial mean body weight, respectively, by the end of 6 weeks. Presence of plastic bags in the rumen could interfere with digestion, with a gradual loss in body weight, productivity and occasional mortality. Plastic bags in the rumen should be considered as a differential diagnosis in sheep presenting the observed clinical signs, especially in urban and periurban areas