Background. Familial Mediterranean fever (FMF) is an auto-inflammatory disease characterized by periodic episodes of fever and recurrent polyserositis. It is caused by a dysfunction of pyrin (or marenostrin) as a result of various mutations within the MEFV gene, some causing very severe cases, while others may result in milder signs and symptoms. Case report. We report the case of a family in which 4 members displayed similar symptoms and were confirmed genetically with mutations characteristic for FMF. The 4 members displaying signs of FMF are the father and the 3 out of 6 siblings (2 males and 1 female). The main presenting complaint in all members is the recurrent abdominal pain. The father which tested genetically as follows - FMF-V726A carrier; FMF-E148Q homozygote, at the age of 45 started having recurrent attacks of unspecified abdominal pain, followed by diarrhea, and he was diagnosed with FMF, based on a family history of FMF in his brother. Later on the disease was confirmed genetically. Although, the onset is considered to be at the age 45, there is a history of left knee effusion at age 18 due to strenuous exercises in the army. Additionally he presents with polyarthralgia and stiffness over the day especially in left knee, both elbows and interphalangeal joints. Sibling no.1 – a 27 y.o. male with onset of disease at age 27 presents with attacks of appendicitis-like pain, cramps and flatulence, without diarrhea associated with recurrent left knee arthralgia. Average duration of attacks is of 2-3 days a month with milder symptoms after starting colchicine use. Has a history of knee arthritis at the age of 10, chest stabbing pain during deep breath (pleuritic chest pain), and one episode of erythema nodosum on both shins resolved within a couple of weeks after the attack. Genetic testing revealed FMFV726A heterozygote; FMF-E148Q heterozygote. Sibling no.2 – a 26 y.o. male with disease onset at the age 23 with attacks of generalized peritoneal pain followed by diarrhea, stabbing chest pain aggravated by deep breath (pleuritic chest pain), no joints symptoms. Genetic testing revealed FMF-V726A heterozygote; FMF-E148Q heterozygote. Sibling no. 3 – a 15 y.o. female with onset of disease at age 9, with menstruation related attacks of generalized peritoneal pain followed by diarrhea, pain in both knees and generalized weakness. Genetic testing revealed FMF-V726A heterozygote; FMF-E148Q heterozygote. All patients manage to control the disease with diet and colchicine. Conclusions. Although traditionally fever is a considered a hallmark of FMF, with the discovery of genetic mutations, we can confirm a greater variety of clinical presentation, not all cases presenting with all classical symptoms. The described family presents with mainly peritoneal symptoms and all siblings display the same mutations FMF-V726A heterozygote and FMF-E148Q heterozygote.