BACKGROUND. The aim of this study has been to analyze the development of pandemic influenza (H1N1) 2009 in La Rioja autonomous (cases in primary healthcare and cases hospitalized). METHODS. We have included all cases with 2009 H1N1 influenza from week 28-2009 to 3-2010. The main information was collected through Primary Healthcare databases (OMI), lists of Preventive Medicine Hospital Departments, reference laboratory and individual standardized forms. This information was analyzed and described according to week, sex, age, comorbidities, clinical development and medical complication. We explore the association of to antiviral treatment and risk factors. This association was assessed using odds ratios (OR) and 95% confidence interval (CI). Adjustment for confounders was performed using unconditional logistic regression to estimate the odds ratio (OR) and 95% confidence intervals (CI). RESULTS. From 29-2009 week to 3-2010 week, a total of 7096 pandemic influenza A(H1N1) cases were notified from Primary Healthcare and 111 laboratory confirmed severe cases were admitted to hospital. Five cases were admitted to an ICU (4,5%) and 2 cases died. All this patients had comorbidities. None of children and pregnant female were admitted to an ICU. CONCLUSIONS. Children and young person have been population with more cases of pandemic influenza (H1N1) 2009. Clinical evolution of pandemic in the majority cases in La Rioja, has been mild.