COVID-19 is associated with increased morbidity and mortality in transplant recipients . There are no efficacy data available regarding these patients with any of the available SARS-CoV-2 vaccines . We analyzed the humoral response following full vaccination with the BNT162b2 (Pfizer-BioNTech) in 136 kidney transplant recipients, and compared it to 25 controls . In order to exclude prior exposure to the virus, only participants with negative serology to SARS-CoV-2 nucleocapsid protein were included . All controls developed a positive response to spike protein, while only 51/136 transplant recipients (37.5 %) had positive serology (p <0.001). Mean IgG anti-spike level was higher in the controls (31.05 (41.8) vs 200.5 (65.1) AU/mL, study vs control, respectively, p <0.001). Variables associated with null humoral response were older age [odds ratio 1.66 (95% confidence interval 1.17-2.69) ], high dose corticosteroids in the last 12 months [1.3 (1.09-1.86) ], maintenance with triple immunosuppression [1.43 (1.06-2.15) ], and regimen that includes mycophenolate [1.47 (1.26-2.27) ]. There was a similar rate of side effects between controls and recipients, and no correlation was found between presence of symptoms to seroconversion . Our findings suggest that most kidney transplant recipients remain at high risk for COVID-19 despite vaccination . Further studies regarding possible measures to increase recipient's response to vaccination are required.