Stratospheric measurements of the C2H6 mixing ratio up to 30 km and of the C3H8 mixing ratio up to 18 km altitude are reported. The observed vertical gradient of C2H6 is much weaker than that calculated from a one-dimensional steady state model, indicating lower concentrations of atomic chlorine in the lower stratosphere than those predicted by models. From measured C2H6 profile a tentative estimate for the Cl concentration is derived.