Objective: To investigate Blastocystis' etiologic role and association with gastrointestinal symptomatology in acute and chronic urticaria patients and to identify Blastocystis subtypes responsible for urticaria. Methods: The study included urticaria patients and healthy individuals that presented to our polyclinic between June 2015 and May 2017. The participants were assigned into Group I (137 patients), subdivided into acute (72) and chronic urticaria patients (65), and Group ? (129 control individuals). Blastocystis presence was investigated by native-Lugol examination, trichrome staining, PCR using sequence tagged site primers, and DNA sequencing analysis. The phylogenetic tree was constructed. Results: The native-Lugol and trichrome staining methods revealed that 16 patients (16/133, 12.0%) had Blastocystis-positive stool samples, of which seven samples (7/133, 5.3%) belonged acute and nine (9/133, 6.8%) to chronic urticaria patients. Concerning Blastocystis subtypes, of the acute urticaria patients, three had subtype 1 (ST1), one had ST2, and three had ST3. Of the chronic urticaria patients, one had ST1 and eight had ST3. Blastocystis positivity was detected in two control individuals (2/123, 1.6%), both being ST3. All subtypes identified by PCR were confirmed by the sequencing analysis. The acute and chronic urticaria groups showed no statistically significant differences for Blastocystis positivity (P=0.60) and subtype distribution (P=0.15). A statistically significant difference was found between the urticaria patients and the controls for Blastocystis positivity (P<0.01), but not for subtype distribution (P=0.67) or for Blastocystis presence and gastrointestinal complaints. Conclusions: This study on Blastocystis subtype distribution among Turkish urticaria patients showed results consistent with the literature. It was concluded that Blastocystis should be kept in mind in patients with urticaria.