Microplastic particles with a size of less than 5 mm make up a significant component of the plastic pollution in freshwater and the ocean. This study was designed to investigate the effects of eight-week exposure to high-molecular-weight polyvinyl chloride (HMW-PVC) on young rats. A total of 40 rats were divided into two assay groups of 15 rats (Group 1, Group 2, a total of 30 rats) and a control group of 10 rats. The rats in the first and second assay groups were fed with food containing HMW-PVC at rates of 1 and 2% of their weight, respectively. The control group was fed food without HMW-PVC. The rats’ weights were recorded every 15 days. After eight weeks of feeding, the rats’ intestines, kidneys, and livers were removed and underwent histopathological examinations. Additionally, mRNA expression levels of Cyp3A2, Pepck, and Fasn genes in the liver, UT-A1, UT-A2, renin, and Cyp27B1 genes in the kidney, and Muc2, Fabp2, and PepT1 genes in the intestine were determined by using the RT-PCR technique. Our study revealed that rats exposed to microplastic particles exhibited non-significant weight loss and obvious organ degeneration. Furthermore, mRNA expression levels of the examined genes were either elevated or suppressed by regular exposure to high-molecular-weight PVC.