The photoconductivity of 0·1 μm films of lead telluride has been investigated using 100 ns light pulses. Films protected from oxygen exposure were insensitive to light; exposed films showed considerable photoconductivity, with a decay time of 3 × 10⁻⁶ s at 77 K. The results were quantitatively consistent with a lowering of intergranular potential barriers which exist in oxygen-exposed films.