Background:  Calprotectin is a marker of inflammation as it is a cytosolic protein in the neutrophilic granulocytes.
Objectives: We aimedto assess fecal calprotectin (FC) in the inflammatory, infectious and malignant gastrointestinal (G.I.T) diseases.
Patients and Methods: 169 patients presented with G.I.T symptoms and proved with inflammatory, infectious or malignant condition by histopathological examination of the G.I.T endoscopic specimens were recruited. Symptomatic subjects with normal findings were considered as a non-organic; comparable group. Complete blood count, E.S.R, C.R.P, liver function tests, kidney function tests and stool analysis followed by endoscopic examination and multiple biopsies were taken for histopathological examination. FC was measured for all subjects.  
Results: Out of 169 patients; 79 patients (53.7%) showed inflammatory/infectious lesions (34 of them were inflammatory bowel disease (I.B.D)), 68 (46.3%) were malignant lesions and, 22 of them showed non-organic lesions (13%). FC levels (median, IQR; interquartile range) were significantly higher in inflammatory, infection group and malignant group than in the non-organic group (145 (53-2467) and 136 (45-212) versus 17 (10-57) respectively, P value =0.000). Patients with I.B.D showed significantly higher values for FC than in those with non I.B.D, P value= 0.000. Colorectal cancer patients showed higher FC values than gastric or esophageal cancer, P value= 0.000.
Conclusions: FC is a useful marker in the diagnosis of G.I.T inflammatory, infectious and malignant conditions especially in I.B.D and colorectal cancer.