A turbidimeter has been developed for rapid, automatic, and precise cloud-curve measurements in polymer solutions. The apparatus combines five sample cells in a single unit and so permits five different compositions to be studied in a single heating or cooling ramp, leading to rapid characterization of the cloud curve. The apparatus can be used in the temperature range 293 to 523 K at pressures up to approximately 3 MPa. The instrument was tested in measurements on the system PS + cyclohexane, where PS is polystyrene, and subsequently used to measure the cloud curves of PMMA + cyclohexanol and PS-b-MMA + cyclohexanol, where PMMA is poly(methyl methacrylate) and PS-b-MMA is a 50:50 block copolymer formed from styrene and methyl methacrylate. The effect of polymer molar mass was studied. All systems showed upper critical solution temperatures.