This volume contains the selected contributed papers from the BIOMAT 2009 — Ninth International Symposium on Mathematical and Computational Biology and the contributions of the Keynote Speakers which present the state of the art of fundamental topics of interdisciplinary science to research groups and interested individuals on the mathematical modelling of biological phenomena. New results are presented on cells, particularly their growth rate and fractal behavior of colony contours; on control mechanisms of molecular systems; the Monte–Carlo simulation of protein models; and on fractal and nonlinear analysis of biochemical time series. There are also new results on population dynamics, such as the paleodemography of New Zealand and a comprehensive review on complex food webs. Contributions on computational biology include the use of graph partitioning to analyse biological networks and graph theory in chemosystematics. The studies of infectious diseases include the dynamics of reinfection of Tuberculosis; the spread of HIV infection in the immune system and the real-time forecasting of an Influenza pandemic in the UK. New contributions to the field of modelling of physiological disorders include the study of macrophages and tumours and the influence of microenvironment on tumour cells proliferation and migration.