Gaya district has been endemic for malaria since long. Southern blocks of the district are malaria endemic. However, the malaria outbreak was reported from northern blocks in 2015 where since past few years reported malarial cases have been negligible. Epidemiological, Entomological and Environmental investigations were done to understand the causes of the outbreak and suggest remedial measures. Total 874 cases of malaria were reported in Gaya in 2015 from 3 blocks viz: Pariaya, Town block and Tekari. Slide Positivity Rate (SPR) was highest in Tekari (79.67%)>Town block (48.7%)>Pariaya (18.74%). Slide Falciparum & Slide Vivax Rate (SPR/SVR) was highest in Tekari (8.13%/69.9%)>Town Block (1.9%/35.37%)>Pariaya (0.2%/18.2%).Proportion of falciparum cases were highest in Tekari (10.20%)>Town block (3.97%)>Pariaya (1.28%). Larval index in all potential breeding sources was high, thus favouring disease transmission. Most of the affected population belonged to low socio-economic strata, with most of the houses being semi –pucca/ or mud-plastered category. The report establishes that the malaria outbreak in Gaya in 2015 was not a seasonal phenomenon rather was an outbreak and the vectors are establishing new niches for disease transmission.