Objective:To determine the range and incidence of complications associated with Plasmodium vivax (P. vivax) malaria. Methods: A retrospective analysis was performed of all patients of P. vivax malaria admitted in Kasturba Medical College, Manipal between January and December, 2010. Patients with mixed malarial infection were excluded by appropriate tests. Clinical presentation and laboratory parameters were studied. Results: Medical records of 213 individuals who satisfied the inclusion criteria were reviewed. Anaemia was seen in 65 (30.5%), leucopenia in 38 (17.8%) and thrombocytopenia in 184 (86.4%) patients. Aspartate and alanine aminotransferases were elevated in 86 (40.4%), and 89 (41.9%) patients respectively. Hypoalbuminemia was observed in 157 (73.6%) cases. Elevated serum creatinine was noted in in 59 (27.5%) patients. Creatine kinase was elevated in 30 out of 59 patients (50.8%). Overall, 107 (50.2%) patients fulfilled WHO criteria for sever=e malaria. None of the patients succumbed to the disease. Conclusion:P. vivax malaria is a potentially severe disease, and the term“benign”tertian malaria is a misnomer. Despite significant morbidity, with timely and appropriate treatment P. vivax malaria has an excellent outcome.