Objective: Congenital anosmia is extremely rare and tends to present late. We report on a series of patients with congenital anosmia to analyze its clinical characteristics and present illustrative cases. Design: Retrospective chart review. Settings: Tertiary care centre. Methods: Thirty-five patients with congenital anosmia were reviewed. A thorough medical history taking, physical examination, and nasal endoscopy were performed in all patients. T&T olfactory testing (n = 33), olfactory event-related potentials (OERPs) (n = 33), and sinonasal computed tomography (CT) (n = 35) were carried out. Magnetic resonance images (MRIs) of the olfactory pathway (n = 34) were available. Serum sex hormones were tested (n = 33). Main Outcome Measures: Physical examination, olfactory testing, MRI of the olfactory pathway, and serum sex hormones. Results: Twenty cases were isolated congenital anosmia (ICA). Fifteen cases were congenital anosmia with other anomalies, including 12 cases with Kallmann syndrome (KS), two with CHARGE syndrome, and one with hypoplasia of the nasal cavity and nasal sinus. T&T olfactory testing indicated anosmia (n = 33). No OERP was obtained (n = 33). CT scans indicated three abnormal patients, including two with unilateral choanal atresia and one with hypoplasia of the nasal cavity and sinus. MRI demonstrated aplasia or hypoplasia of the olfactory bulbs, tracts, and olfactory sulci (n = 34). Serum sex hormones were low in 12 patients with KS. Conclusions: Early diagnosis of congenital anosmia on the basis of olfactory symptoms is difficult. MRI of the olfactory pathway plays an important role in anatomic location. ICA is the most common congenital anosmia. KS is the primary presentation of congenital anosmia with other anomalies.