A study was carried out with the objective of determining the haematological and blood biochemical parameters in sheep and goats with plastic bags in the rumen for a period of 42 days. This was to indicate the possible influence of plastic bags in the rumen on blood parameters. 16, one-year old castrate Dorper sheep with a mean body weight of 26.8 kg (± 0.3 kg) and 16 one-year old castrate small East African goats with a mean weight of 24.5 kg (± 0.3 kg) were used for the study. The 16 sheep and 16 goats were divided into 4 groups of 4 animals each (n = 4). Three groups of each species were implanted with 129 g, 258 g and 387 g of plastic bags, respectively, in the rumen through rumenotomy and the fourth group of each species was control on which rumenotomy was done but with no implanting of plastic bags. Blood samples were obtained by jugular venipuncture from all sheep and goats every 2 weeks for analysis. The only haematological parameter that had significant change was platelets, which significantly (p < 0.05) increased in both sheep and goats with plastic bags in the rumen. However, mean values of erythrocytes, packed cell volume, haemoglobin and mean corpuscular volume decreased but not significantly in the sheep and goats with plastic bags in the rumen. The sheep and goats with plastic bags in the rumen had hyponatraemmia, hypochloridaemia and decreased aspartate aminotransferase enzyme activity. The changes observed in haematological and biochemical parameters could be an indication of adverse effects on the production and well-being of sheep and goats that ingest these plastic bags. These finding may be of diagnostic importance in cases of rumen impaction with indigestible foreign bodies, particularly, plastic bags.