A review was made on notorious insect pests and diseases of crops, resulting about 25-35% yield loss annually in Nepal. Among the insect pests; brown planthopper (Nilaparvata lugens) in rice, cotton bollworm (Helicoverpa armigera) in various crops, armyworm (Mythimna separate) in rice and maize, white stemborer (Xylotrechus quadripes) in coffee, Potato tuber moth (Phthorimaea operculella) and red ants (Dorylus orientalis) in potato are causing periodically havoc. Whiteflies, mealybugs and leaf miners are emerging as major pests. Recently introduced South American tomato leaf miner (Tuta absoluta) in tomato, officially identified in 2016 from Kathmandu valley is reported as possible dangerous pest. Similarly, blast (Magnaporthe grisea) and bacterial leaf blight of rice, late blight and bacterial wilt of tomato and potato, club root and black rot of crucifers, downy mildew and virus complex of cucumber, citrus greening (Liberobacter asiaticum), leaf and stripe rusts of wheat, northern leaf blight of maize, panama wilt of banana etc. are considered as major diseases of economic importance. Bacterial stem rot (Erwinia caratova) of tomato and gray leaf spot (Cercospora zea maydis) of maize are emerging for significant yield loss. The newly introduced coffee rust (Hemileia vastatrix) is now becoming serious threat to coffee plantation. Fall armyworm (Spodoptera frugiperda) and UG99 virulence race of Puccinia graminis need to prevent becoming dangerous from their entry. This review would be helpful to policy planning, future research and extension works.