This is a cross-sectional study done on 70 patients with familial Mediterranean fever (FMF) already diagnosed clinically, according to genetic mutations and they were followed-up at the Rheumatology Clinic, Children's Hospital - Cairo University, to detect variable clinical presentations of heterozygous group of FMF patients and efficacy of Colchicine therapy trial in treatment of heterozygous group of FMF after one year. Homozygous and gene-ve groups of FMF patients were included in our study for more comparison. Our data indicated that fever, abdominal pain and arthritis were the most frequent presentations and response to Colchicine was incomplete in 74.3% of patients. In conclusion heterozygous patients presenting with severe phenotype should be further analyzed for less common second MEFV mutation using gene sequencing.