Abstract: An apparatus for microbiological analysis of biological samples in liquid suspension by light-scattering technique, which employs test-tube containers (11) made of a material transparent to electromagnetic radiations of a determined wave length. Each container (11) cooperating with a thermostat system (17) and at least momentarily with a stirring assembly (31) and relative keeper stirring means (18). The container (11) cooperating with a focussing and collimation system (22) and with a monitoring device (24), is illuminated by electromagnetic radiation of a determined wave length (74) emitted with its own axis (29) of emission and transmitted through the container (11) by the focussing and collimation system (22). The radiation is scattered by any microorganisms present in the sample with an intensity related to their number and morphology. This scattered radiation is picked-up in succession with desired timing by the monitoring device (24) according to determined angles, from 0.degree. to 180.degree.