Diagnosis and treatment of vomiting and diarrhea in dogs and cats is based on anamnestic data and a clinical picture according to which a detailed diagnostic protocol is planned. Vomiting is defined as a reflex, developed for the purpose of protecting the macroorganism from ingested toxins, but it is also found as a simptom in many pathological conditions. If vomiting lasts for 10 or more days then we are talking about chronic vomiting. The main causes of vomiting are of the systemic, metabolic and endocrine nature, but vomiting can also be the rezault of many infectious, neoplastic, mechanical and toxic disorders in the gastroenteric tract, pancreas, liver and the bile duct. Diarrhea is defined as an increase in the volume and substence of the intestinal content and also in its discharge rate. It is further characterised by the nature of the pathophisiological mechanism behind it, its anatomical location (small intestine or the colon), and the duration ( acute and chronic). Diarrhea is considered acute if it lasts less than 14 days. The main causes of diarrhea are parasitic invasions, IBD, neoplasia, food intolerance, viral and chronic bacterial infections. There are four main mechanisms that cause diarrhea and they are called osmotic diarrhea, secretory diarrhea, increased mucosal permeability, deranged motility. In the process of coming up with the final and most precise diagnosis for the cause of vomiting and diarrhea in dongs and cats methods and procedures like the complete blood count, biochemistry panel, parasitological and virological tests of stool, abdominal X-rays, ultrasound and endoscopic procedures with tissue biopsies are essential. The therapy of vomiting and diarrhea in dogs and cats is carried out based on their etiology. The therapeutical protocol shold resolve around a light, dietary nutrition and the use of drugs like aniemetics, gastroprotectants, antisecretionl drugs, antibiotics, corticosteoids and imunnomodulatory drugs.