The aim of this study was to determine whether the inhalation of formaldehyde has a neurotoxicological impact. Forty Wistar rats (Lew.1/K) were trained to find food in a maze within a particular time. When all animals were at an equal level, 13 rats inhaled 2.6 ppm and 13 others inhaled 4.6 ppm formaldehyde 10 min/d, 7 d/week for 90 d. The control group comprised 14 animals inhaling water steam according to the same exposure pattern. During the exposure period and the post-trial observation stage (30 d), the time required to find the food and the number of mistakes made on the way were recorded. Between the animals exposed to formaldehyde and the control group a statistically significant difference for both parameters was observed (p < 0.05). The animals exposed to formaldehyde needed more time and made more mistakes than the animals of the control group while going through the maze. The results underline the necessity for a systematic observance of precautions in case of occupational or dwelling-related formaldehyde exposure, and allow us to classify formaldehyde as "probably neurotoxic". Further investigations are required to assess the neurotoxicologic impact of subchronic formaldehyde exposure.