<p>This experimental work is conducted to study the viability of Azolla algae methyl ester blends as a fuel in a compression ignition engine. This experimental work explores the influence of compression ratio on performance and emission parameters of diesel engine while operating on Azolla methyl ester blends. Performance and emission parameters of diesel engine fueled with 20 percentage, 30 percentage and 40 percentage blends of Azolla methyl ester with diesel under varying compression ratios. The result in general indicated enhanced combustion with increasing AME blends and compression ratios as brake thermal efficiency increased, carbon monoxide emissions decreased and oxides of nitrogen increased. The experimental results emphasize the intricate interplay between engine load, biodiesel percentage and compression ratio on the performance and emissions characteristics of CI engines.</p>