Data from the general population suggest that fatality rates declined during the course of the pandemic. This analysis, using data extracted from the Brazilian Kidney Transplant COVID-19 Registry, seeks to determine fatality rates over time since the index case on March 3rd, 2020. Data from hospitalized patients with RT-PCR positive SARS-CoV-2 infection from March to August 2020 (35 sites, 878 patients) were compared using trend tests according to quartiles (Q1: <72 days; Q2: 72–104 days; Q3: 105–140 days; Q4: >140 days after the index case). The 28-day fatality decreased from 29.5% (Q1) to 18.8% (Q4) (p_for-trend = 0.004). In multivariable analysis, patients diagnosed in Q4 showed a 35% reduced risk of death. The trend of reducing fatality was associated with a lower number of comorbidities (20.7–10.6%, p_for-trend = 0.002), younger age (55–53 years, p_for-trend = 0.062), and better baseline renal function (43.6–47.7 ml/min/1.73 m², p_for-trend = 0.060), and were confirmed by multivariable analysis. The proportion of patients presenting dyspnea (p_for-trend = 0.001) and hypoxemia (p_for-trend < 0.001) at diagnosis, and requiring intensive care was also found reduced (p_for-trend = 0.038). Despite possible confounding variables and time-dependent sampling differences, we conclude that COVID-19-associated fatality decreased over time. Differences in demographics, clinical presentation, and treatment options might be involved.