Giardia lamblia is one of the parasites affecting gastrointestinal tract causing diarrhea. Recurrent
diarrhea may be associated with decreased serum level of vitamin D. The present
study determined the vitamin D level in Giardia lamblia infected patients and the relation between
G. lamblia infection and vitamin D deficiency among patients with acute or chronic diarrhea
selected from those attended Sohag University Hospitals clinics, from February 2021
to February 2022. A total of 192 patients with acute and chronic diarrhea selected from both
sexes, 96 patients (62 rural, 34 urban) were G. lamblia positive with ages ranged from 3 to 63
years. Of the cross-matched 96/204selected control (59 rural, 37 urban) were negative for G.
lamblia. Serum 25-OH vitamin D estimated by ELISA showed significant decrease in mean
level in patients than in controls.