Background: Active search of celiac disease (CD) among risk groups has significantly increased the scope of known clinical variants. Aim: To measure the frequency and clinical characteristics of CD among first degree relatives (FDR) of known celiac cases. Material and methods: Between January 2012-August 2013, 37 patients with celiac disease brought 113 FDR for assessment. Their clinical data was recorded and a blood sample was obtained to measure serum Immunoglobulin A (IgA) levels, anti-transglutaminase (tTG) and anti-endomisial (EMA) antibodies. Cases with positive serology were advised to have an intestinal biopsy. Results: Fourteen relatives (12.4%) had positive serological results and none had IgA deficiency. Among IgA-tTG(-) cases, measurement of IgA/IgG-tTG identified an additional case. Two of the 14 relatives were EMA positive. All 14 cases were advised to have an intestinal biopsy, but only 6 accepted the procedure. In two, the intestinal lesion was classified Marsh ?2 and active CD was diagnosed. Histology in the remaining four was Marsh 0/1 and were diagnosed potential CD, remaining under control, without gluten free diet. Conclusions: Serological prevalence of CD among first degree relatives of known celiac cases was 15 fold greater than in THE general Chilean population, strongly supporting the idea of implementing active search to customary clinical practice. Determination of IgA/IgG-tTG may be useful to improve the yield of active search. Intestinal biopsies were crucial to differentiate active classic CD from potential CD.Background: Active search of celiac disease (CD) among risk groups has significantly increased the scope of known clinical variants. Aim: To measure the frequency and clinical characteristics of CD among first degree relatives (FDR) of known celiac cases. Material and methods: Between January 2012-August 2013, 37 patients with celiac disease brought 113 FDR for assessment. Their clinical data was recorded and a blood sample was obtained to measure serum Immunoglobulin A (IgA) levels, anti-transglutaminase (tTG) and anti-endomisial (EMA) antibodies. Cases with positive serology were advised to have an intestinal biopsy. Results: Fourteen relatives (12.4%) had positive serological results and none had IgA deficiency. Among IgA-tTG(-) cases, measurement of IgA/IgG-tTG identified an additional case. Two of the 14 relatives were EMA positive. All 14 cases were advised to have an intestinal biopsy, but only 6 accepted the procedure. In two, the intestinal lesion was classified Marsh ?2 and active CD was diagnosed. Histology in the remaining four was Marsh 0/1 and were diagnosed potential CD, remaining under control, without gluten free diet. Conclusions: Serological prevalence of CD among first degree relatives of known celiac cases was 15 fold greater than in THE general Chilean population, strongly supporting the idea of implementing active search to customary clinical practice. Determination of IgA/IgG-tTG may be useful to improve the yield of active search. Intestinal biopsies were crucial to differentiate active classic CD from potential CD.