Thermoelectric power and Hall effect were measured for Pb 1−x −y Sn y Mn x Te samples with 0.00 ≤ x ≤ 0.12 and 0.72 ≤ y ≤ 0.80, with carrier concentration 1.9 × 10 20 ≤ p ≤ 2.5 × 10 21 cm −3 over a temperature range T = 4.2-300 K. The analysis of the experimental data based on a two-valence-band model was performed. The theoretical description of the light holes of the L band is based on the Dimmock model. For heavy holes from the band the parabolic dispersion relation was assumed. Our analysis indicates that with increasing Mn content the energy gap (E g ) increases: ∂E g /∂x = 25 meV at.% −1 , whereas the energy separation between the bands of light and heavy holes (E ) decreases: ∂E /∂x = −12 meV at.% −1 . We also observe an increase of the effective mass of heavy holes (m ) from m = (1.0 ± 0.25)m 0 for samples with x ≤ 0.09 to m = 2.1m 0 for x = 0.12.