The objectives of this study were to determine the percutaneous absorption of alach‐lor relative to formulation dilution with water, and to determine the ability of soap and water, and of water only, to remove alachlor from skin, relative to time. Alachlor is a preemergence herbicide. The in vivo percutaneous absorption of alachlor in rhesus monkeys was 17.3 ± 3.3, 15.3 ± 3.9, and 21.4 ± 14.2% for 24‐h skin exposure to Lasso formulation diluted 1:20, 1: 40, and 1: 80, respectively. In vivo, there was no support for increased alachlor skin absorption with water dilution, as previously reported for in vitro absorption. The average in vivo absorption of 18% applied dose over 24 h (0.75%/h) was similar to the maximum in vitro rate of 0.8%/h using human skin and human plasma as receptor fluid. Dose accountability in vivo was 80.6–95.2%. [14CJAIachlor in Lasso diluted 1 : 20 with water was placed on rhesus monkeys at concentrations of 23 μg/10 μl/cm2. Skin decontamination at 0 h with soap and water (50% Ivory liquid 1:1 v/v with water) removed 73 ± 15.8% (n ‐ 4) of the applied dose with the first wash; this increased to a total of 82.3 ± 14.8% with two additional washes. Decontamination after 1 h removed 87.5 ± 12.4% with three successive washes. After 3 h decontamination ability decreased, and after 24 h only 51.9 ± 12.2% could be recovered with three successive washes. Using water only, at 0 h 36.6 ± 12.3% alachlor was removed with the first wash and the total increased to 56.0 ± 14.0% with two additional washes. At 24 h the total amount decreased to 28.7 ± 72.2% for three successive washes.