In this work we calculate the S-1(0) gap energies of Lambda hyperons i
n neutron star matter. The calculation is based on a solution of the B
CS gap equation for an effective G-matrix parametrization of the Lambd
a-Lambda interaction with a nuclear matter background, presented recen
tly by Lanskoy and Yamamoto. We find that a gap energy of a few tenths
of a MeV is expected for Lambda Fermi momenta up to about 1.3 fm(-1).
Implications for neutron star matter are examined, and suggest the ex
istence of a Lambda S-1(0) superfluid between the threshold baryon den
sity for Lambda formation and the baryon density where the Lambda frac
tion reaches 15-20 %.