Late blight is economically important disease of members of family Solanaceae caused by Phytophthora species. The most devastating blight is late blight of potato caused by an Oomycete fungus like organism Phytopthora infestans which was responsible for the death of one million Irish people and massive migration of people from Ireland to neighboring countries in 1840s by triggering potato famine known as the Great Irish Famine in the history. Phytophthora infestans, today, is still as active as it was in 1845, rather more aggressive than it was before, with the only difference that today we have cure of the disease in the form of fungicides and disease resistant varieties. The pathogen is still problematic and every year it causes huge monitory losses and pose threats to potato production throughout the world. Late blight disease still challenges all those who are concerned with potato production despite we have sufficient knowledge about the pathogen and its control strategies. This book briefly discuses history of late blight of potato, biology of Phytophthora infestans and control measures of late blight disease.