Lameness is one of the most prevalent diseases affecting the welfare of cows in modern dairy production. It leads to behavioral changes in severely lame cows, which have been investigated in much detail. For early detection of lameness, knowledge of the effects of moderate lameness on cow behavior is crucial. Therefore, the behavior of non-lame and moderately lame cows was compared on 17 Swiss dairy farms. On each farm, 5-11 non-lame (locomotion score 1 of 5) and 2-7 moderately lame (locomotion score 3 of 5) cows were selected for data collection in two 48-h periods (A, B) separated by an interval of 6-10 wk. Based on visual locomotion scoring, 142 non-lame cows and 66 moderately lame were examined in period A and 128 non-lame and 53 moderately lame cows in period B. Between these two periods, the cows underwent corrective hoof trimming. Lying behavior, locomotor activity, and neck activity were recorded by accelerometers (MSR145 data logger), feeding and rumination behaviors by noseband sensors (RumiWatch halter). Furthermore, visits to the brush and the concentrate feeder and the milking order position were recorded. In comparison with non-lame cows, moderately lame cows had a longer lying duration, a longer average lying bout duration, and a greater lateral asymmetry in lying duration. Furthermore, average locomotor activity, locomotor activity during 1 h after feed delivery or push-ups, and average neck activity were lower in moderately lame cows. Eating time and the number of eating chews (jaw movements) were reduced in moderately lame compared with non-lame cows, whereas no effect of moderate lameness was evident for ruminating time, number of ruminating chews and boluses, and average number of ruminating chews per bolus. Moderately lame cows visited the concentrate feeder and the brush less frequently, and they were further back in the milking order compared with non-lame cows. In conclusion, non-lame and moderately lame cows differed in a biologically relevant way in many of the behavioral variables investigated in this study. Therefore, the use of these behavioral changes seems to be promising to elaborate a tool for early lameness detection.