A positive chemotaxis to sugars (maltose, sucrose, and xylose) and mannite has been studied by the capillary method in the Chlamydomonas reinhardtii strain 495 with negative phototaxis. The addition of an attractant to the suspension of mobile cells temporarily inhibited the photoresponse at a light intensity of 6 and 18 W/m², while at 90 W/m², no inhibitory effect of the attractant was observed. The phototaxis response was completely restored after the period of time necessary for cell adaptation to a chemical effector. The adaptation time was 15-20 min in our experiments. Glucose did not serve as an attractant for mobile Chlamydomonas cells and did not affect their photoresponse. Chemotaxis was similar in the Chlamydomonas wild type strain and the mutant one with negative phototaxis.