A system for the rapid analysis of microbiological parameters includes a specimen container for containing a liquid sample, a housing having an enclosable chamber shaped for receiving the specimen container, an incubating system mounted within the housing for incubating microbiological materials within the liquid sample, and a spectrophotometer system mounted within the housing for measuring light absorbed, emitted or scattered by the liquid samples as the microbiological materials are incubated by the incubating system over time. The specimen container is filled with a liquid sample to be tested and mixed with a reagent that provides a detectable parameter, and placed inside the apparatus. The incubation system heats and maintains the temperature of the liquid sample within a preset range while the spectrophotometer system propagates light within the specimen container, and monitors and records changes in the light as the light propagates through the container. A continuous non-intrusive monitoring and recording of the test parameter is achieved as the incubation progresses. Any significant deviation of the signal output is an indication of presence of the detectable parameter, while the time taken to reach the significant deviation provides quantification of the microbiological parameter under investigation.