The environmental and health issues posed by agro wastes have prompted many researchers to look at an alternate use for these materials. The present work looks at using coir fiber and pith as a substituent in cement blocks. Fillers were subjected to chemical treatments and loaded in cement blocks at different loadings. Compression property and water imbibing of the blocks were studied with respect to loading and chemical treatment. The microbial growths on these blocks were studied using E. coli.