Résumé : A sample of K+μ3 events, detected in the CERN 1.1 m3 heavy-liquid bubble chamber, has been used to investigate the q2 dependence of the form factors, giving ξ(0) = -1.1 ± 1.0 and ξ(6.6m2π) = -0.34 ± 0.20, for λ+ = 0.027. A three parameter fit gives a value for λ+ = 0.025 ± 0.017 in good agreement with the preceding Ke3 analysis. © 1973.