The present work is a revision about neural networks. Initially presents a little introduction to neural networks,fuzzy logic, a brief history, and the applications of Neural Networks on Biotechnology. The chosen sub-areas of theapplications of Neural Networks on Biotechnology are, Solid-State Fermentation Optimization, DNA Sequencing,Molecular Sequencing Analysis, Quantitative Structure-Activity Relationship, Soft Sensing, Spectra Interpretation,Data Mining, each one use a special kind of neural network like feedforward, recurrent, siamese, art, among others.Applications of the Neural-Networks in spectra interpretation and Quantitative Structure-activity relationships, is adirect application to Chemistry and consequently also to Biochemistry and Biotechnology. Soft Sensing is a specialexample for applications on Biotechnology. It is a method to measure variables that normally can’t be directlymeasure. Solid state fermentation was optimized and presenting, as result, a strong increasing of productionefficiency.Keywords: Artificial Neural Networks, Fuzzy Logic, Perceptron, Neural Networks Applications.